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PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) NNNNAAAAMMMMEEEE perlfunc - Perl builtin functions DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN The functions in this section can serve as terms in an expression. They fall into two major categories: list operators and named unary operators. These differ in their precedence relationship with a following comma. (See the precedence table in the _p_e_r_l_o_p manpage.) List operators take more than one argument, while unary operators can never take more than one argument. Thus, a comma terminates the argument of a unary operator, but merely separates the arguments of a list operator. A unary operator generally provides a scalar context to its argument, while a list operator may provide either scalar and list contexts for its arguments. If it does both, the scalar arguments will be first, and the list argument will follow. (Note that there can only ever be one list argument.) For instance, _s_p_l_i_c_e_(_) has three scalar arguments followed by a list. In the syntax descriptions that follow, list operators that expect a list (and provide list context for the elements of the list) are shown with LIST as an argument. Such a list may consist of any combination of scalar arguments or list values; the list values will be included in the list as if each individual element were interpolated at that point in the list, forming a longer single-dimensional list value. Elements of the LIST should be separated by commas. Any function in the list below may be used either with or without parentheses around its arguments. (The syntax descriptions omit the parens.) If you use the parens, the simple (but occasionally surprising) rule is this: It _L_O_O_K_S like a function, therefore it _I_S a function, and precedence doesn't matter. Otherwise it's a list operator or unary operator, and precedence does matter. And whitespace between the function and left parenthesis doesn't count--so you need to be careful sometimes: pppprrrriiiinnnntttt 1111++++2222++++3333;;;; #### PPPPrrrriiiinnnnttttssss 6666.... pppprrrriiiinnnntttt((((1111++++2222)))) ++++ 3333;;;; #### PPPPrrrriiiinnnnttttssss 3333.... pppprrrriiiinnnntttt ((((1111++++2222))))++++3333;;;; #### AAAAllllssssoooo pppprrrriiiinnnnttttssss 3333!!!! pppprrrriiiinnnntttt ++++((((1111++++2222))))++++3333;;;; #### PPPPrrrriiiinnnnttttssss 6666.... pppprrrriiiinnnntttt ((((((((1111++++2222))))++++3333))));;;; #### PPPPrrrriiiinnnnttttssss 6666.... If you run Perl with the ----wwww switch it can warn you about this. For example, the third line above produces: pppprrrriiiinnnntttt ((((............)))) iiiinnnntttteeeerrrrpppprrrreeeetttteeeedddd aaaassss ffffuuuunnnnccccttttiiiioooonnnn aaaatttt ---- lllliiiinnnneeee 1111.... UUUUsssseeeelllleeeessssssss uuuusssseeee ooooffff iiiinnnntttteeeeggggeeeerrrr aaaaddddddddiiiittttiiiioooonnnn iiiinnnn vvvvooooiiiidddd ccccoooonnnntttteeeexxxxtttt aaaatttt ---- lllliiiinnnneeee 1111.... For functions that can be used in either a scalar or list 16/Feb/96 perl 5.002 with 1 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) context, non-abortive failure is generally indicated in a scalar context by returning the undefined value, and in a list context by returning the null list. Remember the following rule: _T_H_E_R_E _I_S _N_O _G_E_N_E_R_A_L _R_U_L_E _F_O_R _C_O_N_V_E_R_T_I_N_G _A _L_I_S_T _I_N_T_O _A _S_C_A_L_A_R_! Each operator and function decides which sort of value it would be most appropriate to return in a scalar context. Some operators return the length of the list that would have been returned in a list context. Some operators return the first value in the list. Some operators return the last value in the list. Some operators return a count of successful operations. In general, they do what you want, unless you want consistency. PPPPeeeerrrrllll FFFFuuuunnnnccccttttiiiioooonnnnssss bbbbyyyy CCCCaaaatttteeeeggggoooorrrryyyy Here are Perl's functions (including things that look like functions, like some of the keywords and named operators) arranged by category. Some functions appear in more than one place. Functions for SCALARs or strings chomp, chop, chr, crypt, hex, index, lc, lcfirst, length, oct, ord, pack, q/STRING/, qq/STRING/, reverse, rindex, sprintf, substr, tr///, uc, ucfirst, y/// Regular expressions and pattern matching m//, pos, quotemeta, s///, split, study Numeric functions abs, atan2, cos, exp, hex, int, log, oct, rand, sin, sqrt, srand Functions for real @ARRAYs pop, push, shift, splice, unshift Functions for list data grep, join, map, qw/STRING/, reverse, sort, unpack Functions for real %HASHes delete, each, exists, keys, values Input and output functions binmode, close, closedir, dbmclose, dbmopen, die, eof, fileno, flock, format, getc, print, printf, read, readdir, rewinddir, seek, seekdir, select, syscall, sysread, syswrite, tell, telldir, truncate, warn, write 16/Feb/96 perl 5.002 with 2 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) Functions for fixed length data or records pack, read, syscall, sysread, syswrite, unpack, vec Functions for filehandles, files, or directories -X, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link, lstat, mkdir, open, opendir, readlink, rename, rmdir, stat, symlink, umask, unlink, utime Keywords related to the control flow of your perl program caller, continue, die, do, dump, eval, exit, goto, last, next, redo, return, sub, wantarray Keywords related to scoping caller, import, local, my, package, use Miscellaneous functions defined, dump, eval, formline, local, my, reset, scalar, undef, wantarray Functions for processes and process groups alarm, exec, fork, getpgrp, getppid, getpriority, kill, pipe, qx/STRING/, setpgrp, setpriority, sleep, system, times, wait, waitpid Keywords related to perl modules do, import, no, package, require, use Keywords related to classes and object-orientedness bless, dbmclose, dbmopen, package, ref, tie, tied, untie, use Low-level socket functions accept, bind, connect, getpeername, getsockname, getsockopt, listen, recv, send, setsockopt, shutdown, socket, socketpair System V interprocess communication functions msgctl, msgget, msgrcv, msgsnd, semctl, semget, semop, shmctl, shmget, shmread, shmwrite Fetching user and group info endgrent, endhostent, endnetent, endpwent, getgrent, getgrgid, getgrnam, getlogin, getpwent, getpwnam, getpwuid, setgrent, setpwent Fetching network info endprotoent, endservent, gethostbyaddr, gethostbyname, gethostent, getnetbyaddr, getnetbyname, getnetent, getprotobyname, getprotobynumber, getprotoent, getservbyname, getservbyport, getservent, sethostent, setnetent, setprotoent, setservent 16/Feb/96 perl 5.002 with 3 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) Time-related functions gmtime, localtime, time, times AAAAllllpppphhhhaaaabbbbeeeettttiiiiccccaaaallll LLLLiiiissssttttiiiinnnngggg ooooffff PPPPeeeerrrrllll FFFFuuuunnnnccccttttiiiioooonnnnssss -X FILEHANDLE -X EXPR -X A file test, where X is one of the letters listed below. This unary operator takes one argument, either a filename or a filehandle, and tests the associated file to see if something is true about it. If the argument is omitted, tests $$$$____, except for ----tttt, which tests STDIN. Unless otherwise documented, it returns 1111 for TRUE and '''''''' for FALSE, or the undefined value if the file doesn't exist. Despite the funny names, precedence is the same as any other named unary operator, and the argument may be parenthesized like any other unary operator. The operator may be any of: ----rrrr FFFFiiiilllleeee iiiissss rrrreeeeaaaaddddaaaabbbblllleeee bbbbyyyy eeeeffffffffeeeeccccttttiiiivvvveeee uuuuiiiidddd////ggggiiiidddd.... ----wwww FFFFiiiilllleeee iiiissss wwwwrrrriiiittttaaaabbbblllleeee bbbbyyyy eeeeffffffffeeeeccccttttiiiivvvveeee uuuuiiiidddd////ggggiiiidddd.... ----xxxx FFFFiiiilllleeee iiiissss eeeexxxxeeeeccccuuuuttttaaaabbbblllleeee bbbbyyyy eeeeffffffffeeeeccccttttiiiivvvveeee uuuuiiiidddd////ggggiiiidddd.... ----oooo FFFFiiiilllleeee iiiissss oooowwwwnnnneeeedddd bbbbyyyy eeeeffffffffeeeeccccttttiiiivvvveeee uuuuiiiidddd.... ----RRRR FFFFiiiilllleeee iiiissss rrrreeeeaaaaddddaaaabbbblllleeee bbbbyyyy rrrreeeeaaaallll uuuuiiiidddd////ggggiiiidddd.... ----WWWW FFFFiiiilllleeee iiiissss wwwwrrrriiiittttaaaabbbblllleeee bbbbyyyy rrrreeeeaaaallll uuuuiiiidddd////ggggiiiidddd.... ----XXXX FFFFiiiilllleeee iiiissss eeeexxxxeeeeccccuuuuttttaaaabbbblllleeee bbbbyyyy rrrreeeeaaaallll uuuuiiiidddd////ggggiiiidddd.... ----OOOO FFFFiiiilllleeee iiiissss oooowwwwnnnneeeedddd bbbbyyyy rrrreeeeaaaallll uuuuiiiidddd.... ----eeee FFFFiiiilllleeee eeeexxxxiiiissssttttssss.... ----zzzz FFFFiiiilllleeee hhhhaaaassss zzzzeeeerrrroooo ssssiiiizzzzeeee.... ----ssss FFFFiiiilllleeee hhhhaaaassss nnnnoooonnnn----zzzzeeeerrrroooo ssssiiiizzzzeeee ((((rrrreeeettttuuuurrrrnnnnssss ssssiiiizzzzeeee)))).... ----ffff FFFFiiiilllleeee iiiissss aaaa ppppllllaaaaiiiinnnn ffffiiiilllleeee.... ----dddd FFFFiiiilllleeee iiiissss aaaa ddddiiiirrrreeeeccccttttoooorrrryyyy.... ----llll FFFFiiiilllleeee iiiissss aaaa ssssyyyymmmmbbbboooolllliiiicccc lllliiiinnnnkkkk.... ----pppp FFFFiiiilllleeee iiiissss aaaa nnnnaaaammmmeeeedddd ppppiiiippppeeee ((((FFFFIIIIFFFFOOOO)))).... ----SSSS FFFFiiiilllleeee iiiissss aaaa ssssoooocccckkkkeeeetttt.... ----bbbb FFFFiiiilllleeee iiiissss aaaa bbbblllloooocccckkkk ssssppppeeeecccciiiiaaaallll ffffiiiilllleeee.... ----cccc FFFFiiiilllleeee iiiissss aaaa cccchhhhaaaarrrraaaacccctttteeeerrrr ssssppppeeeecccciiiiaaaallll ffffiiiilllleeee.... ----tttt FFFFiiiilllleeeehhhhaaaannnnddddlllleeee iiiissss ooooppppeeeennnneeeedddd ttttoooo aaaa ttttttttyyyy.... ----uuuu FFFFiiiilllleeee hhhhaaaassss sssseeeettttuuuuiiiidddd bbbbiiiitttt sssseeeetttt.... ----gggg FFFFiiiilllleeee hhhhaaaassss sssseeeettttggggiiiidddd bbbbiiiitttt sssseeeetttt.... ----kkkk FFFFiiiilllleeee hhhhaaaassss ssssttttiiiicccckkkkyyyy bbbbiiiitttt sssseeeetttt.... ----TTTT FFFFiiiilllleeee iiiissss aaaa tttteeeexxxxtttt ffffiiiilllleeee.... ----BBBB FFFFiiiilllleeee iiiissss aaaa bbbbiiiinnnnaaaarrrryyyy ffffiiiilllleeee ((((ooooppppppppoooossssiiiitttteeee ooooffff ----TTTT)))).... 16/Feb/96 perl 5.002 with 4 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ----MMMM AAAAggggeeee ooooffff ffffiiiilllleeee iiiinnnn ddddaaaayyyyssss wwwwhhhheeeennnn ssssccccrrrriiiipppptttt ssssttttaaaarrrrtttteeeedddd.... ----AAAA SSSSaaaammmmeeee ffffoooorrrr aaaacccccccceeeessssssss ttttiiiimmmmeeee.... ----CCCC SSSSaaaammmmeeee ffffoooorrrr iiiinnnnooooddddeeee cccchhhhaaaannnnggggeeee ttttiiiimmmmeeee.... The interpretation of the file permission operators ----rrrr, ----RRRR, ----wwww, ----WWWW, ----xxxx and ----XXXX is based solely on the mode of the file and the uids and gids of the user. There may be other reasons you can't actually read, write or execute the file. Also note that, for the superuser, ----rrrr, ----RRRR, ----wwww and ----WWWW always return 1, and ----xxxx and ----XXXX return 1 if any execute bit is set in the mode. Scripts run by the superuser may thus need to do a _s_t_a_t_(_) in order to determine the actual mode of the file, or temporarily set the uid to something else. Example: wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ cccchhhhoooopppp;;;; nnnneeeexxxxtttt uuuunnnnlllleeeessssssss ----ffff $$$$____;;;; #### iiiiggggnnnnoooorrrreeee ssssppppeeeecccciiiiaaaallllssss ............ }}}} Note that ----ssss////aaaa////bbbb//// does not do a negated substitution. Saying ----eeeexxxxpppp(((($$$$ffffoooooooo)))) still works as expected, however--only single letters following a minus are interpreted as file tests. The ----TTTT and ----BBBB switches work as follows. The first block or so of the file is examined for odd characters such as strange control codes or characters with the high bit set. If too many odd characters (>30%) are found, it's a ----BBBB file, otherwise it's a ----TTTT file. Also, any file containing null in the first block is considered a binary file. If ----TTTT or ----BBBB is used on a filehandle, the current stdio buffer is examined rather than the first block. Both ----TTTT and ----BBBB return TRUE on a null file, or a file at EOF when testing a filehandle. Because you have to read a file to do the ----TTTT test, on most occasions you want to use a ----ffff against the file first, as in nnnneeeexxxxtttt uuuunnnnlllleeeessssssss ----ffff $$$$ffffiiiilllleeee &&&&&&&& ----TTTT $$$$ffffiiiilllleeee. If any of the file tests (or either the _s_t_a_t_(_) or _l_s_t_a_t_(_) operators) are given the special filehandle consisting of a solitary underline, then the stat structure of the previous file test (or stat operator) is used, saving a system call. (This doesn't work with ----tttt, and you need to remember that _l_s_t_a_t_(_) and ----llll will leave values in the stat structure for the symbolic link, not the real file.) Example: 16/Feb/96 perl 5.002 with 5 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) pppprrrriiiinnnntttt """"CCCCaaaannnn ddddoooo....\\\\nnnn"""" iiiiffff ----rrrr $$$$aaaa |||||||| ----wwww ____ |||||||| ----xxxx ____;;;; ssssttttaaaatttt(((($$$$ffffiiiilllleeeennnnaaaammmmeeee))));;;; pppprrrriiiinnnntttt """"RRRReeeeaaaaddddaaaabbbblllleeee\\\\nnnn"""" iiiiffff ----rrrr ____;;;; pppprrrriiiinnnntttt """"WWWWrrrriiiittttaaaabbbblllleeee\\\\nnnn"""" iiiiffff ----wwww ____;;;; pppprrrriiiinnnntttt """"EEEExxxxeeeeccccuuuuttttaaaabbbblllleeee\\\\nnnn"""" iiiiffff ----xxxx ____;;;; pppprrrriiiinnnntttt """"SSSSeeeettttuuuuiiiidddd\\\\nnnn"""" iiiiffff ----uuuu ____;;;; pppprrrriiiinnnntttt """"SSSSeeeettttggggiiiidddd\\\\nnnn"""" iiiiffff ----gggg ____;;;; pppprrrriiiinnnntttt """"SSSSttttiiiicccckkkkyyyy\\\\nnnn"""" iiiiffff ----kkkk ____;;;; pppprrrriiiinnnntttt """"TTTTeeeexxxxtttt\\\\nnnn"""" iiiiffff ----TTTT ____;;;; pppprrrriiiinnnntttt """"BBBBiiiinnnnaaaarrrryyyy\\\\nnnn"""" iiiiffff ----BBBB ____;;;; abs VALUE Returns the absolute value of its argument. accept NEWSOCKET,GENERICSOCKET Accepts an incoming socket connect, just as the _a_c_c_e_p_t(2) system call does. Returns the packed address if it succeeded, FALSE otherwise. See example in the section on _S_o_c_k_e_t_s_: _C_l_i_e_n_t_/_S_e_r_v_e_r _C_o_m_m_u_n_i_c_a_t_i_o_n in the _p_e_r_l_i_p_c manpage. alarm SECONDS Arranges to have a SIGALRM delivered to this process after the specified number of seconds have elapsed. (On some machines, unfortunately, the elapsed time may be up to one second less than you specified because of how seconds are counted.) Only one timer may be counting at once. Each call disables the previous timer, and an argument of 0 may be supplied to cancel the previous timer without starting a new one. The returned value is the amount of time remaining on the previous timer. For delays of finer granularity than one second, you may use Perl's _s_y_s_c_a_l_l_(_) interface to access _s_e_t_i_t_i_m_e_r(2) if your system supports it, or else see the sssseeeelllleeeecccctttt(((()))) entry elsewhere in this documentbelow. It is not advised to intermix _a_l_a_r_m_(_) and _s_l_e_e_p_(_) calls. atan2 Y,X Returns the arctangent of Y/X in the range -pi to pi. bind SOCKET,NAME Binds a network address to a socket, just as the bind system call does. Returns TRUE if it succeeded, FALSE otherwise. NAME should be a packed address of the appropriate type for the socket. See the examples in the section on _S_o_c_k_e_t_s_: _C_l_i_e_n_t_/_S_e_r_v_e_r _C_o_m_m_u_n_i_c_a_t_i_o_n in the 16/Feb/96 perl 5.002 with 6 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) _p_e_r_l_i_p_c manpage. binmode FILEHANDLE Arranges for the file to be read or written in "binary" mode in operating systems that distinguish between binary and text files. Files that are not in binary mode have CR LF sequences translated to LF on input and LF translated to CR LF on output. Binmode has no effect under Unix; in DOS and similarly archaic systems, it may be imperative--otherwise your DOS-damaged C library may mangle your file. The key distinction between systems that need binmode and those that don't is their text file formats. Systems like Unix and Plan9 that delimit lines with a single character, and that encode that character in C as '\n', do not need bbbbiiiinnnnmmmmooooddddeeee. The rest need it. If FILEHANDLE is an expression, the value is taken as the name of the filehandle. bless REF,CLASSNAME bless REF This function tells the referenced object (passed as REF) that it is now an object in the CLASSNAME package--or the current package if no CLASSNAME is specified, which is often the case. It returns the reference for convenience, since a _b_l_e_s_s_(_) is often the last thing in a constructor. Always use the two-argument version if the function doing the blessing might be inherited by a derived class. See the _p_e_r_l_o_b_j manpage for more about the blessing (and blessings) of objects. caller EXPR caller Returns the context of the current subroutine call. In a scalar context, returns TRUE if there is a caller, that is, if we're in a subroutine or _e_v_a_l_(_) or _r_e_q_u_i_r_e_(_), and FALSE otherwise. In a list context, returns (((($$$$ppppaaaacccckkkkaaaaggggeeee,,,, $$$$ffffiiiilllleeeennnnaaaammmmeeee,,,, $$$$lllliiiinnnneeee)))) ==== ccccaaaalllllllleeeerrrr;;;; With EXPR, it returns some extra information that the debugger uses to print a stack trace. The value of EXPR indicates how many call frames to go back before the current one. (((($$$$ppppaaaacccckkkkaaaaggggeeee,,,, $$$$ffffiiiilllleeeennnnaaaammmmeeee,,,, $$$$lllliiiinnnneeee,,,, $$$$ssssuuuubbbbrrrroooouuuuttttiiiinnnneeee,,,, $$$$hhhhaaaassssaaaarrrrggggssss,,,, $$$$wwwwaaaannnnttttaaaarrrrggggssss)))) ==== ccccaaaalllllllleeeerrrr(((($$$$iiii))));;;; Furthermore, when called from within the DB package, caller returns more detailed information: 16/Feb/96 perl 5.002 with 7 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) it sets the list variable @@@@DDDDBBBB::::::::aaaarrrrggggssss to be the arguments with which that subroutine was invoked. chdir EXPR Changes the working directory to EXPR, if possible. If EXPR is omitted, changes to home directory. Returns TRUE upon success, FALSE otherwise. See example under _d_i_e_(_). chmod LIST Changes the permissions of a list of files. The first element of the list must be the numerical mode, which should probably be an octal number. Returns the number of files successfully changed. $$$$ccccnnnntttt ==== cccchhhhmmmmoooodddd 0000777755555555,,,, ''''ffffoooooooo'''',,,, ''''bbbbaaaarrrr'''';;;; cccchhhhmmmmoooodddd 0000777755555555,,,, @@@@eeeexxxxeeeeccccuuuuttttaaaabbbblllleeeessss;;;; chomp VARIABLE chomp LIST chomp This is a slightly safer version of chop (see below). It removes any line ending that corresponds to the current value of $$$$//// (also known as $$$$IIIINNNNPPPPUUUUTTTT____RRRREEEECCCCOOOORRRRDDDD____SSSSEEEEPPPPAAAARRRRAAAATTTTOOOORRRR in the EEEEnnnngggglllliiiisssshhhh module). It returns the number of characters removed. It's often used to remove the newline from the end of an input record when you're worried that the final record may be missing its newline. When in paragraph mode ($$$$//// ==== """"""""), it removes all trailing newlines from the string. If VARIABLE is omitted, it chomps $$$$____. Example: wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ cccchhhhoooommmmpppp;;;; #### aaaavvvvooooiiiidddd \\\\nnnn oooonnnn llllaaaasssstttt ffffiiiieeeelllldddd @@@@aaaarrrrrrrraaaayyyy ==== sssspppplllliiiitttt((((////::::////))));;;; ............ }}}} You can actually chomp anything that's an lvalue, including an assignment: cccchhhhoooommmmpppp(((($$$$ccccwwwwdddd ==== ````ppppwwwwdddd````))));;;; cccchhhhoooommmmpppp(((($$$$aaaannnnsssswwwweeeerrrr ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>))));;;; If you chomp a list, each element is chomped, and the total number of characters removed is returned. chop VARIABLE 16/Feb/96 perl 5.002 with 8 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) chop LIST chop Chops off the last character of a string and returns the character chopped. It's used primarily to remove the newline from the end of an input record, but is much more efficient than ssss////\\\\nnnn//////// because it neither scans nor copies the string. If VARIABLE is omitted, chops $$$$____. Example: wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ cccchhhhoooopppp;;;; #### aaaavvvvooooiiiidddd \\\\nnnn oooonnnn llllaaaasssstttt ffffiiiieeeelllldddd @@@@aaaarrrrrrrraaaayyyy ==== sssspppplllliiiitttt((((////::::////))));;;; ............ }}}} You can actually chop anything that's an lvalue, including an assignment: cccchhhhoooopppp(((($$$$ccccwwwwdddd ==== ````ppppwwwwdddd````))));;;; cccchhhhoooopppp(((($$$$aaaannnnsssswwwweeeerrrr ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>))));;;; If you chop a list, each element is chopped. Only the value of the last chop is returned. Note that chop returns the last character. To return all but the last character, use ssssuuuubbbbssssttttrrrr(((($$$$ssssttttrrrriiiinnnngggg,,,, 0000,,,, ----1111)))). chown LIST Changes the owner (and group) of a list of files. The first two elements of the list must be the _N_U_M_E_R_I_C_A_L uid and gid, in that order. Returns the number of files successfully changed. $$$$ccccnnnntttt ==== cccchhhhoooowwwwnnnn $$$$uuuuiiiidddd,,,, $$$$ggggiiiidddd,,,, ''''ffffoooooooo'''',,,, ''''bbbbaaaarrrr'''';;;; cccchhhhoooowwwwnnnn $$$$uuuuiiiidddd,,,, $$$$ggggiiiidddd,,,, @@@@ffffiiiilllleeeennnnaaaammmmeeeessss;;;; Here's an example that looks up non-numeric uids in the passwd file: pppprrrriiiinnnntttt """"UUUUsssseeeerrrr:::: """";;;; cccchhhhoooopppp(((($$$$uuuusssseeeerrrr ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>))));;;; pppprrrriiiinnnntttt """"FFFFiiiilllleeeessss:::: """" cccchhhhoooopppp(((($$$$ppppaaaatttttttteeeerrrrnnnn ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>))));;;; (((($$$$llllooooggggiiiinnnn,,,,$$$$ppppaaaassssssss,,,,$$$$uuuuiiiidddd,,,,$$$$ggggiiiidddd)))) ==== ggggeeeettttppppwwwwnnnnaaaammmm(((($$$$uuuusssseeeerrrr)))) oooorrrr ddddiiiieeee """"$$$$uuuusssseeeerrrr nnnnooootttt iiiinnnn ppppaaaasssssssswwwwdddd ffffiiiilllleeee"""";;;; @@@@aaaarrrryyyy ==== <<<<$$$${{{{ppppaaaatttttttteeeerrrrnnnn}}}}>>>>;;;; #### eeeexxxxppppaaaannnndddd ffffiiiilllleeeennnnaaaammmmeeeessss cccchhhhoooowwwwnnnn $$$$uuuuiiiidddd,,,, $$$$ggggiiiidddd,,,, @@@@aaaarrrryyyy;;;; On most systems, you are not allowed to change the ownership of the file unless you're the superuser, 16/Feb/96 perl 5.002 with 9 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) although you should be able to change the group to any of your secondary groups. On insecure systems, these restrictions may be relaxed, but this is not a portable assumption. chr NUMBER Returns the character represented by that NUMBER in the character set. For example, cccchhhhrrrr((((66665555)))) is "A" in ASCII. chroot FILENAME This function works as the system call by the same name: it makes the named directory the new root directory for all further pathnames that begin with a "/" by your process and all of its children. (It doesn't change your current working directory is unaffected.) For security reasons, this call is restricted to the superuser. If FILENAME is omitted, does chroot to $$$$____. close FILEHANDLE Closes the file or pipe associated with the file handle, returning TRUE only if stdio successfully flushes buffers and closes the system file descriptor. You don't have to close FILEHANDLE if you are immediately going to do another _o_p_e_n_(_) on it, since _o_p_e_n_(_) will close it for you. (See _o_p_e_n_(_).) However, an explicit close on an input file resets the line counter ($.), while the implicit close done by _o_p_e_n_(_) does not. Also, closing a pipe will wait for the process executing on the pipe to complete, in case you want to look at the output of the pipe afterwards. Closing a pipe explicitly also puts the status value of the command into $$$$????. Example: ooooppppeeeennnn((((OOOOUUUUTTTTPPPPUUUUTTTT,,,, ''''||||ssssoooorrrrtttt >>>>ffffoooooooo''''))));;;; #### ppppiiiippppeeee ttttoooo ssssoooorrrrtttt ............ #### pppprrrriiiinnnntttt ssssttttuuuuffffffff ttttoooo oooouuuuttttppppuuuutttt cccclllloooosssseeee OOOOUUUUTTTTPPPPUUUUTTTT;;;; #### wwwwaaaaiiiitttt ffffoooorrrr ssssoooorrrrtttt ttttoooo ffffiiiinnnniiiisssshhhh ooooppppeeeennnn((((IIIINNNNPPPPUUUUTTTT,,,, ''''ffffoooooooo''''))));;;; #### ggggeeeetttt ssssoooorrrrtttt''''ssss rrrreeeessssuuuullllttttssss FILEHANDLE may be an expression whose value gives the real filehandle name. closedir DIRHANDLE Closes a directory opened by _o_p_e_n_d_i_r_(_). connect SOCKET,NAME Attempts to connect to a remote socket, just as the connect system call does. Returns TRUE if it succeeded, FALSE otherwise. NAME should be a packed address of the appropriate type for the socket. See the examples in the section on _S_o_c_k_e_t_s_: _C_l_i_e_n_t_/_S_e_r_v_e_r _C_o_m_m_u_n_i_c_a_t_i_o_n in the 16/Feb/96 perl 5.002 with 10 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) _p_e_r_l_i_p_c manpage. continue BLOCK Actually a flow control statement rather than a function. If there is a ccccoooonnnnttttiiiinnnnuuuueeee BLOCK attached to a BLOCK (typically in a wwwwhhhhiiiilllleeee or ffffoooorrrreeeeaaaacccchhhh), it is always executed just before the conditional is about to be evaluated again, just like the third part of a ffffoooorrrr loop in C. Thus it can be used to increment a loop variable, even when the loop has been continued via the nnnneeeexxxxtttt statement (which is similar to the C ccccoooonnnnttttiiiinnnnuuuueeee statement). cos EXPR Returns the cosine of EXPR (expressed in radians). If EXPR is omitted takes cosine of $$$$____. crypt PLAINTEXT,SALT Encrypts a string exactly like the _c_r_y_p_t(3) function in the C library (assuming that you actually have a version there that has not been extirpated as a potential munition). This can prove useful for checking the password file for lousy passwords, amongst other things. Only the guys wearing white hats should do this. Here's an example that makes sure that whoever runs this program knows their own password: $$$$ppppwwwwdddd ==== ((((ggggeeeettttppppwwwwuuuuiiiidddd(((($$$$<<<<))))))))[[[[1111]]]];;;; $$$$ssssaaaalllltttt ==== ssssuuuubbbbssssttttrrrr(((($$$$ppppwwwwdddd,,,, 0000,,,, 2222))));;;; ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy ----eeeecccchhhhoooo"""";;;; pppprrrriiiinnnntttt """"PPPPaaaasssssssswwwwoooorrrrdddd:::: """";;;; cccchhhhoooopppp(((($$$$wwwwoooorrrrdddd ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>))));;;; pppprrrriiiinnnntttt """"\\\\nnnn"""";;;; ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy eeeecccchhhhoooo"""";;;; iiiiffff ((((ccccrrrryyyypppptttt(((($$$$wwwwoooorrrrdddd,,,, $$$$ssssaaaalllltttt)))) nnnneeee $$$$ppppwwwwdddd)))) {{{{ ddddiiiieeee """"SSSSoooorrrrrrrryyyy............\\\\nnnn"""";;;; }}}} eeeellllsssseeee {{{{ pppprrrriiiinnnntttt """"ooookkkk\\\\nnnn"""";;;; }}}} Of course, typing in your own password to whoever asks you for it is unwise. dbmclose ASSOC_ARRAY [This function has been superseded by the _u_n_t_i_e_(_) function.] Breaks the binding between a DBM file and an associative array. 16/Feb/96 perl 5.002 with 11 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) dbmopen ASSOC,DBNAME,MODE [This function has been superseded by the _t_i_e_(_) function.] This binds a _d_b_m(3), _n_d_b_m(3), _s_d_b_m(3), _g_d_b_m_(_), or Berkeley DB file to an associative array. ASSOC is the name of the associative array. (Unlike normal open, the first argument is _N_O_T a filehandle, even though it looks like one). DBNAME is the name of the database (without the _._d_i_r or _._p_a_g extension if any). If the database does not exist, it is created with protection specified by MODE (as modified by the _u_m_a_s_k_(_)). If your system only supports the older DBM functions, you may perform only one _d_b_m_o_p_e_n_(_) in your program. In older versions of Perl, if your system had neither DBM nor ndbm, calling _d_b_m_o_p_e_n_(_) produced a fatal error; it now falls back to _s_d_b_m(3). If you don't have write access to the DBM file, you can only read associative array variables, not set them. If you want to test whether you can write, either use file tests or try setting a dummy array entry inside an _e_v_a_l_(_), which will trap the error. Note that functions such as _k_e_y_s_(_) and _v_a_l_u_e_s_(_) may return huge array values when used on large DBM files. You may prefer to use the _e_a_c_h_(_) function to iterate over large DBM files. Example: #### pppprrrriiiinnnntttt oooouuuutttt hhhhiiiissssttttoooorrrryyyy ffffiiiilllleeee ooooffffffffsssseeeettttssss ddddbbbbmmmmooooppppeeeennnn((((%%%%HHHHIIIISSSSTTTT,,,,''''////uuuussssrrrr////lllliiiibbbb////nnnneeeewwwwssss////hhhhiiiissssttttoooorrrryyyy'''',,,,0000666666666666))));;;; wwwwhhhhiiiilllleeee (((((((($$$$kkkkeeeeyyyy,,,,$$$$vvvvaaaallll)))) ==== eeeeaaaacccchhhh %%%%HHHHIIIISSSSTTTT)))) {{{{ pppprrrriiiinnnntttt $$$$kkkkeeeeyyyy,,,, '''' ==== '''',,,, uuuunnnnppppaaaacccckkkk((((''''LLLL'''',,,,$$$$vvvvaaaallll)))),,,, """"\\\\nnnn"""";;;; }}}} ddddbbbbmmmmcccclllloooosssseeee((((%%%%HHHHIIIISSSSTTTT))));;;; See also the _A_n_y_D_B_M___F_i_l_e manpage for a more general description of the pros and cons of the various dbm apparoches, as well as the _D_B___F_i_l_e manpage for a particularly rich implementation. defined EXPR Returns a boolean value saying whether EXPR has a real value or not. Many operations return the undefined value under exceptional conditions, such as end of file, uninitialized variable, system error and such. This function allows you to distinguish between an undefined null scalar and a defined null scalar with operations that might return a real null string, such as referencing 16/Feb/96 perl 5.002 with 12 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) elements of an array. You may also check to see if arrays or subroutines exist. Use of defined on predefined variables is not guaranteed to produce intuitive results. When used on a hash array element, it tells you whether the value is defined, not whether the key exists in the hash. Use _e_x_i_s_t_s_(_) for that. Examples: pppprrrriiiinnnntttt iiiiffff ddddeeeeffffiiiinnnneeeedddd $$$$sssswwwwiiiittttcccchhhh{{{{''''DDDD''''}}}};;;; pppprrrriiiinnnntttt """"$$$$vvvvaaaallll\\\\nnnn"""" wwwwhhhhiiiilllleeee ddddeeeeffffiiiinnnneeeedddd(((($$$$vvvvaaaallll ==== ppppoooopppp((((@@@@aaaarrrryyyy))))))));;;; ddddiiiieeee """"CCCCaaaannnn''''tttt rrrreeeeaaaaddddlllliiiinnnnkkkk $$$$ssssyyyymmmm:::: $$$$!!!!"""" uuuunnnnlllleeeessssssss ddddeeeeffffiiiinnnneeeedddd(((($$$$vvvvaaaalllluuuueeee ==== rrrreeeeaaaaddddlllliiiinnnnkkkk $$$$ssssyyyymmmm))));;;; eeeevvvvaaaallll ''''@@@@ffffoooooooo ==== (((())))'''' iiiiffff ddddeeeeffffiiiinnnneeeedddd((((@@@@ffffoooooooo))));;;; ddddiiiieeee """"NNNNoooo XXXXYYYYZZZZ ppppaaaacccckkkkaaaaggggeeee ddddeeeeffffiiiinnnneeeedddd"""" uuuunnnnlllleeeessssssss ddddeeeeffffiiiinnnneeeedddd %%%%____XXXXYYYYZZZZ;;;; ssssuuuubbbb ffffoooooooo {{{{ ddddeeeeffffiiiinnnneeeedddd &&&&$$$$bbbbaaaarrrr ???? &&&&$$$$bbbbaaaarrrr((((@@@@____)))) :::: ddddiiiieeee """"NNNNoooo bbbbaaaarrrr"""";;;; }}}} See also _u_n_d_e_f_(_). Note: many folks tend to overuse _d_e_f_i_n_e_d_(_), and then are surprised to discover that the number 0 and the null string are, in fact, defined concepts. For example, if you say """"aaaabbbb"""" ====~~~~ ////aaaa((((....****))))bbbb////;;;; the pattern match succeeds, and $$$$1111 is defined, despite the fact that it matched "nothing". But it didn't really match nothing--rather, it matched something that happened to be 0 characters long. This is all very above-board and honest. When a function returns an undefined value, it's an admission that it couldn't give you an honest answer. So you should only use _d_e_f_i_n_e_d_(_) when you're questioning the integrity of what you're trying to do. At other times, a simple comparison to 0 or "" is what you want. delete EXPR Deletes the specified value from its hash array. Returns the deleted value, or the undefined value if nothing was deleted. Deleting from $$$$EEEENNNNVVVV{{{{}}}} modifies the environment. Deleting from an array tied to a DBM file deletes the entry from the DBM file. (But deleting from a _t_i_e_(_)d hash doesn't necessarily return anything.) The following deletes all the values of an associative array: 16/Feb/96 perl 5.002 with 13 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ffffoooorrrreeeeaaaacccchhhh $$$$kkkkeeeeyyyy ((((kkkkeeeeyyyyssss %%%%AAAARRRRRRRRAAAAYYYY)))) {{{{ ddddeeeelllleeeetttteeee $$$$AAAARRRRRRRRAAAAYYYY{{{{$$$$kkkkeeeeyyyy}}}};;;; }}}} (But it would be faster to use the _u_n_d_e_f_(_) command.) Note that the EXPR can be arbitrarily complicated as long as the final operation is a hash key lookup: ddddeeeelllleeeetttteeee $$$$rrrreeeeffff---->>>>[[[[$$$$xxxx]]]][[[[$$$$yyyy]]]]{{{{$$$$kkkkeeeeyyyy}}}};;;; die LIST Outside of an _e_v_a_l_(_), prints the value of LIST to SSSSTTTTDDDDEEEERRRRRRRR and exits with the current value of $! (errno). If $! is 0, exits with the value of (((($$$$???? >>>>>>>> 8888)))) (backtick `command` status). If (((($$$$???? >>>>>>>> 8888)))) is 0, exits with 255. Inside an _e_v_a_l_(_), the error message is stuffed into $$$$@@@@, and the _e_v_a_l_(_) is terminated with the undefined value; this makes _d_i_e_(_) the way to raise an exception. Equivalent examples: ddddiiiieeee """"CCCCaaaannnn''''tttt ccccdddd ttttoooo ssssppppoooooooollll:::: $$$$!!!!\\\\nnnn"""" uuuunnnnlllleeeessssssss cccchhhhddddiiiirrrr ''''////uuuussssrrrr////ssssppppoooooooollll////nnnneeeewwwwssss'''';;;; cccchhhhddddiiiirrrr ''''////uuuussssrrrr////ssssppppoooooooollll////nnnneeeewwwwssss'''' oooorrrr ddddiiiieeee """"CCCCaaaannnn''''tttt ccccdddd ttttoooo ssssppppoooooooollll:::: $$$$!!!!\\\\nnnn"""" If the value of EXPR does not end in a newline, the current script line number and input line number (if any) are also printed, and a newline is supplied. Hint: sometimes appending ", stopped" to your message will cause it to make better sense when the string "at foo line 123" is appended. Suppose you are running script "canasta". ddddiiiieeee """"////eeeettttcccc////ggggaaaammmmeeeessss iiiissss nnnnoooo ggggoooooooodddd"""";;;; ddddiiiieeee """"////eeeettttcccc////ggggaaaammmmeeeessss iiiissss nnnnoooo ggggoooooooodddd,,,, ssssttttooooppppppppeeeedddd"""";;;; produce, respectively ////eeeettttcccc////ggggaaaammmmeeeessss iiiissss nnnnoooo ggggoooooooodddd aaaatttt ccccaaaannnnaaaassssttttaaaa lllliiiinnnneeee 111122223333.... ////eeeettttcccc////ggggaaaammmmeeeessss iiiissss nnnnoooo ggggoooooooodddd,,,, ssssttttooooppppppppeeeedddd aaaatttt ccccaaaannnnaaaassssttttaaaa lllliiiinnnneeee 111122223333.... See also _e_x_i_t_(_) and _w_a_r_n_(_). do BLOCK Not really a function. Returns the value of the last command in the sequence of commands indicated by BLOCK. When modified by a loop modifier, executes the BLOCK once before testing the loop condition. (On other statements the loop modifiers test the conditional first.) 16/Feb/96 perl 5.002 with 14 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) do SUBROUTINE(LIST) A deprecated form of subroutine call. See the _p_e_r_l_s_u_b manpage. do EXPR Uses the value of EXPR as a filename and executes the contents of the file as a Perl script. Its primary use is to include subroutines from a Perl subroutine library. ddddoooo ''''ssssttttaaaatttt....ppppllll'''';;;; is just like eeeevvvvaaaallll ````ccccaaaatttt ssssttttaaaatttt....ppppllll````;;;; except that it's more efficient, more concise, keeps track of the current filename for error messages, and searches all the ----IIII libraries if the file isn't in the current directory (see also the @@@@IIIINNNNCCCC array in the section on _P_r_e_d_e_f_i_n_e_d _N_a_m_e_s in the _p_e_r_l_v_a_r manpage). It's the same, however, in that it does reparse the file every time you call it, so you probably don't want to do this inside a loop. Note that inclusion of library modules is better done with the _u_s_e_(_) and _r_e_q_u_i_r_e_(_) operators, which also do error checking and raise an exception if there's a problem. dump LABEL This causes an immediate core dump. Primarily this is so that you can use the uuuunnnndddduuuummmmpppp program to turn your core dump into an executable binary after having initialized all your variables at the beginning of the program. When the new binary is executed it will begin by executing a ggggoooottttoooo LLLLAAAABBBBEEEELLLL (with all the restrictions that ggggoooottttoooo suffers). Think of it as a goto with an intervening core dump and reincarnation. If LABEL is omitted, restarts the program from the top. WARNING: any files opened at the time of the dump will NOT be open any more when the program is reincarnated, with possible resulting confusion on the part of Perl. See also ----uuuu option in the _p_e_r_l_r_u_n manpage. Example: 16/Feb/96 perl 5.002 with 15 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ####!!!!////uuuussssrrrr////bbbbiiiinnnn////ppppeeeerrrrllll rrrreeeeqqqquuuuiiiirrrreeee ''''ggggeeeettttoooopppptttt....ppppllll'''';;;; rrrreeeeqqqquuuuiiiirrrreeee ''''ssssttttaaaatttt....ppppllll'''';;;; %%%%ddddaaaayyyyssss ==== (((( ''''SSSSuuuunnnn'''' ====>>>> 1111,,,, ''''MMMMoooonnnn'''' ====>>>> 2222,,,, ''''TTTTuuuueeee'''' ====>>>> 3333,,,, ''''WWWWeeeedddd'''' ====>>>> 4444,,,, ''''TTTThhhhuuuu'''' ====>>>> 5555,,,, ''''FFFFrrrriiii'''' ====>>>> 6666,,,, ''''SSSSaaaatttt'''' ====>>>> 7777,,,, ))));;;; dddduuuummmmpppp QQQQUUUUIIIICCCCKKKKSSSSTTTTAAAARRRRTTTT iiiiffff $$$$AAAARRRRGGGGVVVV[[[[0000]]]] eeeeqqqq ''''----dddd'''';;;; QQQQUUUUIIIICCCCKKKKSSSSTTTTAAAARRRRTTTT:::: GGGGeeeettttoooopppptttt((((''''ffff''''))));;;; each ASSOC_ARRAY Returns a 2-element array consisting of the key and value for the next value of an associative array, so that you can iterate over it. Entries are returned in an apparently random order. When the array is entirely read, a null array is returned (which when assigned produces a FALSE (0) value). The next call to _e_a_c_h_(_) after that will start iterating again. The iterator can be reset only by reading all the elements from the array. You should not add elements to an array while you're iterating over it. There is a single iterator for each associative array, shared by all _e_a_c_h_(_), _k_e_y_s_(_) and _v_a_l_u_e_s_(_) function calls in the program. The following prints out your environment like the _p_r_i_n_t_e_n_v(1) program, only in a different order: wwwwhhhhiiiilllleeee (((((((($$$$kkkkeeeeyyyy,,,,$$$$vvvvaaaalllluuuueeee)))) ==== eeeeaaaacccchhhh %%%%EEEENNNNVVVV)))) {{{{ pppprrrriiiinnnntttt """"$$$$kkkkeeeeyyyy====$$$$vvvvaaaalllluuuueeee\\\\nnnn"""";;;; }}}} See also _k_e_y_s_(_) and _v_a_l_u_e_s_(_). eof FILEHANDLE eof () eof Returns 1 if the next read on FILEHANDLE will return end of file, or if FILEHANDLE is not open. FILEHANDLE may be an expression whose value gives the real filehandle name. (Note that this function actually reads a character and then _u_n_g_e_t_c_(_)s it, so it is not very useful in an interactive context.) Do not read from a terminal 16/Feb/96 perl 5.002 with 16 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) file (or call eeeeooooffff((((FFFFIIIILLLLEEEEHHHHAAAANNNNDDDDLLLLEEEE)))) on it) after end-of- file is reached. Filetypes such as terminals may lose the end-of-file condition if you do. An eeeeooooffff without an argument uses the last file read as argument. Empty parentheses () may be used to indicate the pseudofile formed of the files listed on the command line, i.e. eeeeooooffff(((()))) is reasonable to use inside a while (<>) loop to detect the end of only the last file. Use eeeeooooffff((((AAAARRRRGGGGVVVV)))) or eof without the parentheses to test _E_A_C_H file in a while (<>) loop. Examples: #### rrrreeeesssseeeetttt lllliiiinnnneeee nnnnuuuummmmbbbbeeeerrrriiiinnnngggg oooonnnn eeeeaaaacccchhhh iiiinnnnppppuuuutttt ffffiiiilllleeee wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ pppprrrriiiinnnntttt """"$$$$....\\\\tttt$$$$____"""";;;; cccclllloooosssseeee((((AAAARRRRGGGGVVVV)))) iiiiffff ((((eeeeooooffff))));;;; #### NNNNooootttt eeeeooooffff(((()))).... }}}} #### iiiinnnnsssseeeerrrrtttt ddddaaaasssshhhheeeessss jjjjuuuusssstttt bbbbeeeeffffoooorrrreeee llllaaaasssstttt lllliiiinnnneeee ooooffff llllaaaasssstttt ffffiiiilllleeee wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ iiiiffff ((((eeeeooooffff(((()))))))) {{{{ pppprrrriiiinnnntttt """"--------------------------------------------------------\\\\nnnn"""";;;; cccclllloooosssseeee((((AAAARRRRGGGGVVVV))));;;; #### cccclllloooosssseeee oooorrrr bbbbrrrreeeeaaaakkkk;;;; iiiissss nnnneeeeeeeeddddeeeedddd iiiiffff wwwweeee #### aaaarrrreeee rrrreeeeaaaaddddiiiinnnngggg ffffrrrroooommmm tttthhhheeee tttteeeerrrrmmmmiiiinnnnaaaallll }}}} pppprrrriiiinnnntttt;;;; }}}} Practical hint: you almost never need to use eeeeooooffff in Perl, because the input operators return undef when they run out of data. Testing eeeeooooffff eval EXPR eval BLOCK EXPR is parsed and executed as if it were a little Perl program. It is executed in the context of the current Perl program, so that any variable settings, subroutine or format definitions remain afterwards. The value returned is the value of the last expression evaluated, or a return statement may be used, just as with subroutines. If there is a syntax error or runtime error, or a _d_i_e_(_) statement is executed, an undefined value is returned by _e_v_a_l_(_), and $$$$@@@@ is set to the error message. If there was no error, $$$$@@@@ is guaranteed to be a null string. If EXPR is omitted, evaluates $$$$____. The final semicolon, if any, may be omitted from the expression. Note that, since _e_v_a_l_(_) traps otherwise-fatal errors, it is useful for determining whether a 16/Feb/96 perl 5.002 with 17 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) particular feature (such as _s_o_c_k_e_t_(_) or _s_y_m_l_i_n_k_(_)) is implemented. It is also Perl's exception trapping mechanism, where the die operator is used to raise exceptions. If the code to be executed doesn't vary, you may use the eval-BLOCK form to trap run-time errors without incurring the penalty of recompiling each time. The error, if any, is still returned in $$$$@@@@. Examples: #### mmmmaaaakkkkeeee ddddiiiivvvviiiiddddeeee----bbbbyyyy----zzzzeeeerrrroooo nnnnoooonnnn----ffffaaaattttaaaallll eeeevvvvaaaallll {{{{ $$$$aaaannnnsssswwwweeeerrrr ==== $$$$aaaa //// $$$$bbbb;;;; }}}};;;; wwwwaaaarrrrnnnn $$$$@@@@ iiiiffff $$$$@@@@;;;; #### ssssaaaammmmeeee tttthhhhiiiinnnngggg,,,, bbbbuuuutttt lllleeeessssssss eeeeffffffffiiiicccciiiieeeennnntttt eeeevvvvaaaallll ''''$$$$aaaannnnsssswwwweeeerrrr ==== $$$$aaaa //// $$$$bbbb'''';;;; wwwwaaaarrrrnnnn $$$$@@@@ iiiiffff $$$$@@@@;;;; #### aaaa ccccoooommmmppppiiiilllleeee----ttttiiiimmmmeeee eeeerrrrrrrroooorrrr eeeevvvvaaaallll {{{{ $$$$aaaannnnsssswwwweeeerrrr ==== }}}};;;; #### aaaa rrrruuuunnnn----ttttiiiimmmmeeee eeeerrrrrrrroooorrrr eeeevvvvaaaallll ''''$$$$aaaannnnsssswwwweeeerrrr ===='''';;;; #### sssseeeettttssss $$$$@@@@ With an _e_v_a_l_(_), you should be especially careful to remember what's being looked at when: eeeevvvvaaaallll $$$$xxxx;;;; #### CCCCAAAASSSSEEEE 1111 eeeevvvvaaaallll """"$$$$xxxx"""";;;; #### CCCCAAAASSSSEEEE 2222 eeeevvvvaaaallll ''''$$$$xxxx'''';;;; #### CCCCAAAASSSSEEEE 3333 eeeevvvvaaaallll {{{{ $$$$xxxx }}}};;;; #### CCCCAAAASSSSEEEE 4444 eeeevvvvaaaallll """"\\\\$$$$$$$$xxxx++++++++"""" #### CCCCAAAASSSSEEEE 5555 $$$$$$$$xxxx++++++++;;;; #### CCCCAAAASSSSEEEE 6666 Cases 1 and 2 above behave identically: they run the code contained in the variable $$$$xxxx. (Although case 2 has misleading double quotes making the reader wonder what else might be happening (nothing is).) Cases 3 and 4 likewise behave in the same way: they run the code <$x>, which does nothing at all. (Case 4 is preferred for purely visual reasons.) Case 5 is a place where normally you _W_O_U_L_D like to use double quotes, except that in that particular situation, you can just use symbolic references instead, as in case 6. exec LIST The _e_x_e_c_(_) function executes a system command _A_N_D _N_E_V_E_R _R_E_T_U_R_N_S. Use the _s_y_s_t_e_m_(_) function if you want it to return. If there is more than one argument in LIST, or if LIST is an array with more than one value, calls 16/Feb/96 perl 5.002 with 18 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) _e_x_e_c_v_p(3) with the arguments in LIST. If there is only one scalar argument, the argument is checked for shell metacharacters. If there are any, the entire argument is passed to ////bbbbiiiinnnn////sssshhhh ----cccc for parsing. If there are none, the argument is split into words and passed directly to _e_x_e_c_v_p_(_), which is more efficient. Note: _e_x_e_c_(_) (and _s_y_s_t_e_m(0) do not flush your output buffer, so you may need to set $$$$|||| to avoid lost output. Examples: eeeexxxxeeeecccc ''''////bbbbiiiinnnn////eeeecccchhhhoooo'''',,,, ''''YYYYoooouuuurrrr aaaarrrrgggguuuummmmeeeennnnttttssss aaaarrrreeee:::: '''',,,, @@@@AAAARRRRGGGGVVVV;;;; eeeexxxxeeeecccc """"ssssoooorrrrtttt $$$$oooouuuuttttffffiiiilllleeee |||| uuuunnnniiiiqqqq"""";;;; If you don't really want to execute the first argument, but want to lie to the program you are executing about its own name, you can specify the program you actually want to run as an "indirect object" (without a comma) in front of the LIST. (This always forces interpretation of the LIST as a multi-valued list, even if there is only a single scalar in the list.) Example: $$$$sssshhhheeeellllllll ==== ''''////bbbbiiiinnnn////ccccsssshhhh'''';;;; eeeexxxxeeeecccc $$$$sssshhhheeeellllllll ''''----sssshhhh'''';;;; #### pppprrrreeeetttteeeennnndddd iiiitttt''''ssss aaaa llllooooggggiiiinnnn sssshhhheeeellllllll or, more directly, eeeexxxxeeeecccc {{{{''''////bbbbiiiinnnn////ccccsssshhhh''''}}}} ''''----sssshhhh'''';;;; #### pppprrrreeeetttteeeennnndddd iiiitttt''''ssss aaaa llllooooggggiiiinnnn sssshhhheeeellllllll exists EXPR Returns TRUE if the specified hash key exists in its hash array, even if the corresponding value is undefined. pppprrrriiiinnnntttt """"EEEExxxxiiiissssttttssss\\\\nnnn"""" iiiiffff eeeexxxxiiiissssttttssss $$$$aaaarrrrrrrraaaayyyy{{{{$$$$kkkkeeeeyyyy}}}};;;; pppprrrriiiinnnntttt """"DDDDeeeeffffiiiinnnneeeedddd\\\\nnnn"""" iiiiffff ddddeeeeffffiiiinnnneeeedddd $$$$aaaarrrrrrrraaaayyyy{{{{$$$$kkkkeeeeyyyy}}}};;;; pppprrrriiiinnnntttt """"TTTTrrrruuuueeee\\\\nnnn"""" iiiiffff $$$$aaaarrrrrrrraaaayyyy{{{{$$$$kkkkeeeeyyyy}}}};;;; A hash element can only be TRUE if it's defined, and defined if it exists, but the reverse doesn't necessarily hold true. Note that the EXPR can be arbitrarily complicated as long as the final operation is a hash key lookup: iiiiffff ((((eeeexxxxiiiissssttttssss $$$$rrrreeeeffff---->>>>[[[[$$$$xxxx]]]][[[[$$$$yyyy]]]]{{{{$$$$kkkkeeeeyyyy}}}})))) {{{{ ............ }}}} exit EXPR Evaluates EXPR and exits immediately with that value. (Actually, it calls any defined EEEENNNNDDDD routines first, but the EEEENNNNDDDD routines may not abort 16/Feb/96 perl 5.002 with 19 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) the exit. Likewise any object destructors that need to be called are called before exit.) Example: $$$$aaaannnnssss ==== <<<<SSSSTTTTDDDDIIIINNNN>>>>;;;; eeeexxxxiiiitttt 0000 iiiiffff $$$$aaaannnnssss ====~~~~ ////^^^^[[[[XXXXxxxx]]]]////;;;; See also _d_i_e_(_). If EXPR is omitted, exits with 0 status. exp EXPR Returns _e (the natural logarithm base) to the power of EXPR. If EXPR is omitted, gives eeeexxxxpppp(((($$$$____)))). fcntl FILEHANDLE,FUNCTION,SCALAR Implements the _f_c_n_t_l(2) function. You'll probably have to say uuuusssseeee FFFFccccnnnnttttllll;;;; first to get the correct function definitions. Argument processing and value return works just like _i_o_c_t_l_(_) below. Note that _f_c_n_t_l_(_) will produce a fatal error if used on a machine that doesn't implement _f_c_n_t_l(2). For example: uuuusssseeee FFFFccccnnnnttttllll;;;; ffffccccnnnnttttllll(((($$$$ffffiiiilllleeeehhhhaaaannnnddddlllleeee,,,, FFFF____GGGGEEEETTTTLLLLKKKK,,,, $$$$ppppaaaacccckkkkeeeedddd____rrrreeeettttuuuurrrrnnnn____bbbbuuuuffffffffeeeerrrr))));;;; fileno FILEHANDLE Returns the file descriptor for a filehandle. This is useful for constructing bitmaps for _s_e_l_e_c_t_(_). If FILEHANDLE is an expression, the value is taken as the name of the filehandle. flock FILEHANDLE,OPERATION Calls _f_l_o_c_k(2) on FILEHANDLE. See the _f_l_o_c_k_(_2_) manpage for definition of OPERATION. Returns TRUE for success, FALSE on failure. Will produce a fatal error if used on a machine that doesn't implement either _f_l_o_c_k(2) or _f_c_n_t_l(2). The _f_c_n_t_l(2) system call will be automatically used if _f_l_o_c_k(2) is missing from your system. This makes _f_l_o_c_k_(_) the portable file locking strategy, although it will only lock entire files, not records. Note also that some versions of _f_l_o_c_k_(_) cannot lock things over the network; you would need to use the more system-specific _f_c_n_t_l_(_) for that. Here's a mailbox appender for BSD systems. 16/Feb/96 perl 5.002 with 20 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) $$$$LLLLOOOOCCCCKKKK____SSSSHHHH ==== 1111;;;; $$$$LLLLOOOOCCCCKKKK____EEEEXXXX ==== 2222;;;; $$$$LLLLOOOOCCCCKKKK____NNNNBBBB ==== 4444;;;; $$$$LLLLOOOOCCCCKKKK____UUUUNNNN ==== 8888;;;; ssssuuuubbbb lllloooocccckkkk {{{{ fffflllloooocccckkkk((((MMMMBBBBOOOOXXXX,,,,$$$$LLLLOOOOCCCCKKKK____EEEEXXXX))));;;; #### aaaannnndddd,,,, iiiinnnn ccccaaaasssseeee ssssoooommmmeeeeoooonnnneeee aaaappppppppeeeennnnddddeeeedddd #### wwwwhhhhiiiilllleeee wwwweeee wwwweeeerrrreeee wwwwaaaaiiiittttiiiinnnngggg............ sssseeeeeeeekkkk((((MMMMBBBBOOOOXXXX,,,, 0000,,,, 2222))));;;; }}}} ssssuuuubbbb uuuunnnnlllloooocccckkkk {{{{ fffflllloooocccckkkk((((MMMMBBBBOOOOXXXX,,,,$$$$LLLLOOOOCCCCKKKK____UUUUNNNN))));;;; }}}} ooooppppeeeennnn((((MMMMBBBBOOOOXXXX,,,, """">>>>>>>>////uuuussssrrrr////ssssppppoooooooollll////mmmmaaaaiiiillll////$$$$EEEENNNNVVVV{{{{''''UUUUSSSSEEEERRRR''''}}}}"""")))) oooorrrr ddddiiiieeee """"CCCCaaaannnn''''tttt ooooppppeeeennnn mmmmaaaaiiiillllbbbbooooxxxx:::: $$$$!!!!"""";;;; lllloooocccckkkk(((())));;;; pppprrrriiiinnnntttt MMMMBBBBOOOOXXXX $$$$mmmmssssgggg,,,,""""\\\\nnnn\\\\nnnn"""";;;; uuuunnnnlllloooocccckkkk(((())));;;; See also the _D_B___F_i_l_e manpage for other _f_l_o_c_k_(_) examples. fork Does a _f_o_r_k(2) system call. Returns the child pid to the parent process and 0 to the child process, or uuuunnnnddddeeeeffff if the fork is unsuccessful. Note: unflushed buffers remain unflushed in both processes, which means you may need to set $$$$|||| ($AUTOFLUSH in English) or call the _a_u_t_o_f_l_u_s_h_(_) FileHandle method to avoid duplicate output. If you _f_o_r_k_(_) without ever waiting on your children, you will accumulate zombies: $$$$SSSSIIIIGGGG{{{{CCCCHHHHLLLLDDDD}}}} ==== ssssuuuubbbb {{{{ wwwwaaaaiiiitttt }}}};;;; There's also the double-fork trick (error checking on _f_o_r_k_(_) returns omitted); uuuunnnnlllleeeessssssss (((($$$$ppppiiiidddd ==== ffffoooorrrrkkkk)))) {{{{ uuuunnnnlllleeeessssssss ((((ffffoooorrrrkkkk)))) {{{{ eeeexxxxeeeecccc """"wwwwhhhhaaaatttt yyyyoooouuuu rrrreeeeaaaallllllllyyyy wwwwaaaannnnnnnnaaaa ddddoooo"""";;;; ddddiiiieeee """"nnnnoooo eeeexxxxeeeecccc"""";;;; #### ............ oooorrrr ............ ######## ((((ssssoooommmmeeee____ppppeeeerrrrllll____ccccooooddddeeee____hhhheeeerrrreeee)))) eeeexxxxiiiitttt 0000;;;; }}}} eeeexxxxiiiitttt 0000;;;; }}}} wwwwaaaaiiiittttppppiiiidddd(((($$$$ppppiiiidddd,,,,0000))));;;; 16/Feb/96 perl 5.002 with 21 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) See also the _p_e_r_l_i_p_c manpage for more examples of forking and reaping moribund children. format Declare a picture format with use by the _w_r_i_t_e_(_) function. For example: ffffoooorrrrmmmmaaaatttt SSSSoooommmmeeeetttthhhhiiiinnnngggg ==== TTTTeeeesssstttt:::: @@@@<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< @@@@|||||||||||||||||||| @@@@>>>>>>>>>>>>>>>>>>>> $$$$ssssttttrrrr,,,, $$$$%%%%,,,, ''''$$$$'''' .... iiiinnnntttt(((($$$$nnnnuuuummmm)))) .... $$$$ssssttttrrrr ==== """"wwwwiiiiddddggggeeeetttt"""";;;; $$$$nnnnuuuummmm ==== $$$$ccccoooosssstttt////$$$$qqqquuuuaaaannnnttttiiiiyyyy;;;; $$$$~~~~ ==== ''''SSSSoooommmmeeeetttthhhhiiiinnnngggg'''';;;; wwwwrrrriiiitttteeee;;;; See the _p_e_r_l_f_o_r_m manpage for many details and examples. formline PICTURE, LIST This is an internal function used by ffffoooorrrrmmmmaaaatttts, though you may call it too. It formats (see the _p_e_r_l_f_o_r_m manpage) a list of values according to the contents of PICTURE, placing the output into the format output accumulator, $$$$^^^^AAAA (or $$$$AAAACCCCCCCCUUUUMMMMUUUULLLLAAAATTTTOOOORRRR in English). Eventually, when a _w_r_i_t_e_(_) is done, the contents of $$$$^^^^AAAA are written to some filehandle, but you could also read $$$$^^^^AAAA yourself and then set $$$$^^^^AAAA back to "". Note that a format typically does one _f_o_r_m_l_i_n_e_(_) per line of form, but the _f_o_r_m_l_i_n_e_(_) function itself doesn't care how many newlines are embedded in the PICTURE. This means that the ~~~~ and ~~~~~~~~ tokens will treat the entire PICTURE as a single line. You may therefore need to use multiple formlines to implement a single record format, just like the format compiler. Be careful if you put double quotes around the picture, since an "@@@@" character may be taken to mean the beginning of an array name. _f_o_r_m_l_i_n_e_(_) always returns TRUE. See the _p_e_r_l_f_o_r_m manpage for other examples. getc FILEHANDLE getc Returns the next character from the input file attached to FILEHANDLE, or a null string at end of file. If FILEHANDLE is omitted, reads from STDIN. This is not particularly efficient. It cannot be used to get unbuffered single-characters, however. For that, try something more like: 16/Feb/96 perl 5.002 with 22 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) iiiiffff (((($$$$BBBBSSSSDDDD____SSSSTTTTYYYYLLLLEEEE)))) {{{{ ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy ccccbbbbrrrreeeeaaaakkkk <<<<////ddddeeeevvvv////ttttttttyyyy >>>>////ddddeeeevvvv////ttttttttyyyy 2222>>>>&&&&1111"""";;;; }}}} eeeellllsssseeee {{{{ ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy"""",,,, ''''----iiiiccccaaaannnnoooonnnn'''',,,, ''''eeeeoooollll'''',,,, """"\\\\000000001111"""";;;; }}}} $$$$kkkkeeeeyyyy ==== ggggeeeettttcccc((((SSSSTTTTDDDDIIIINNNN))));;;; iiiiffff (((($$$$BBBBSSSSDDDD____SSSSTTTTYYYYLLLLEEEE)))) {{{{ ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy ----ccccbbbbrrrreeeeaaaakkkk <<<<////ddddeeeevvvv////ttttttttyyyy >>>>////ddddeeeevvvv////ttttttttyyyy 2222>>>>&&&&1111"""";;;; }}}} eeeellllsssseeee {{{{ ssssyyyysssstttteeeemmmm """"ssssttttttttyyyy"""",,,, ''''iiiiccccaaaannnnoooonnnn'''',,,, ''''eeeeoooollll'''',,,, ''''^^^^@@@@'''';;;; #### aaaasssscccciiiiiiii nnnnuuuullllllll }}}} pppprrrriiiinnnntttt """"\\\\nnnn"""";;;; Determination of whether to whether $$$$BBBBSSSSDDDD____SSSSTTTTYYYYLLLLEEEE should be set is left as an exercise to the reader. See also the TTTTeeeerrrrmmmm::::::::RRRReeeeaaaaddddKKKKeeeeyyyy module from your nearest CPAN site; details on CPAN can be found on the CCCCPPPPAAAANNNN entry in the _p_e_r_l_m_o_d manpage getlogin Returns the current login from _/_e_t_c_/_u_t_m_p, if any. If null, use _g_e_t_p_w_u_i_d_(_). $$$$llllooooggggiiiinnnn ==== ggggeeeettttllllooooggggiiiinnnn |||||||| ((((ggggeeeettttppppwwwwuuuuiiiidddd(((($$$$<<<<))))))))[[[[0000]]]] |||||||| """"KKKKiiiillllrrrrooooyyyy"""";;;; Do not consider _g_e_t_l_o_g_i_n_(_) for authorentication: it is not as secure as _g_e_t_p_w_u_i_d_(_). getpeername SOCKET Returns the packed sockaddr address of other end of the SOCKET connection. uuuusssseeee SSSSoooocccckkkkeeeetttt;;;; $$$$hhhheeeerrrrssssoooocccckkkkaaaaddddddddrrrr ==== ggggeeeettttppppeeeeeeeerrrrnnnnaaaammmmeeee((((SSSSOOOOCCCCKKKK))));;;; (((($$$$ppppoooorrrrtttt,,,, $$$$iiiiaaaaddddddddrrrr)))) ==== uuuunnnnppppaaaacccckkkk____ssssoooocccckkkkaaaaddddddddrrrr____iiiinnnn(((($$$$hhhheeeerrrrssssoooocccckkkkaaaaddddddddrrrr))));;;; $$$$hhhheeeerrrrhhhhoooossssttttnnnnaaaammmmeeee ==== ggggeeeetttthhhhoooossssttttbbbbyyyyaaaaddddddddrrrr(((($$$$iiiiaaaaddddddddrrrr,,,, AAAAFFFF____IIIINNNNEEEETTTT))));;;; $$$$hhhheeeerrrrssssttttrrrraaaaddddddddrrrr ==== iiiinnnneeeetttt____nnnnttttooooaaaa(((($$$$iiiiaaaaddddddddrrrr))));;;; getpgrp PID Returns the current process group for the specified PID, 0 for the current process. Will raise an exception if used on a machine that doesn't implement _g_e_t_p_g_r_p(2). If PID is omitted, returns process group of current process. getppid Returns the process id of the parent process. 16/Feb/96 perl 5.002 with 23 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) getpriority WHICH,WHO Returns the current priority for a process, a process group, or a user. (See the _g_e_t_p_r_i_o_r_i_t_y_(_2_) manpage.) Will raise a fatal exception if used on a machine that doesn't implement _g_e_t_p_r_i_o_r_i_t_y(2). getpwnam NAME getgrnam NAME gethostbyname NAME getnetbyname NAME getprotobyname NAME getpwuid UID getgrgid GID getservbyname NAME,PROTO gethostbyaddr ADDR,ADDRTYPE getnetbyaddr ADDR,ADDRTYPE getprotobynumber NUMBER getservbyport PORT,PROTO getpwent getgrent gethostent getnetent getprotoent getservent setpwent setgrent sethostent STAYOPEN setnetent STAYOPEN setprotoent STAYOPEN setservent STAYOPEN 16/Feb/96 perl 5.002 with 24 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) endpwent endgrent endhostent endnetent endprotoent endservent These routines perform the same functions as their counterparts in the system library. Within a list context, the return values from the various get routines are as follows: (((($$$$nnnnaaaammmmeeee,,,,$$$$ppppaaaasssssssswwwwdddd,,,,$$$$uuuuiiiidddd,,,,$$$$ggggiiiidddd,,,, $$$$qqqquuuuoooottttaaaa,,,,$$$$ccccoooommmmmmmmeeeennnntttt,,,,$$$$ggggccccoooossss,,,,$$$$ddddiiiirrrr,,,,$$$$sssshhhheeeellllllll)))) ==== ggggeeeettttppppwwww**** (((($$$$nnnnaaaammmmeeee,,,,$$$$ppppaaaasssssssswwwwdddd,,,,$$$$ggggiiiidddd,,,,$$$$mmmmeeeemmmmbbbbeeeerrrrssss)))) ==== ggggeeeettttggggrrrr**** (((($$$$nnnnaaaammmmeeee,,,,$$$$aaaalllliiiiaaaasssseeeessss,,,,$$$$aaaaddddddddrrrrttttyyyyppppeeee,,,,$$$$lllleeeennnnggggtttthhhh,,,,@@@@aaaaddddddddrrrrssss)))) ==== ggggeeeetttthhhhoooosssstttt**** (((($$$$nnnnaaaammmmeeee,,,,$$$$aaaalllliiiiaaaasssseeeessss,,,,$$$$aaaaddddddddrrrrttttyyyyppppeeee,,,,$$$$nnnneeeetttt)))) ==== ggggeeeettttnnnneeeetttt**** (((($$$$nnnnaaaammmmeeee,,,,$$$$aaaalllliiiiaaaasssseeeessss,,,,$$$$pppprrrroooottttoooo)))) ==== ggggeeeettttpppprrrroooottttoooo**** (((($$$$nnnnaaaammmmeeee,,,,$$$$aaaalllliiiiaaaasssseeeessss,,,,$$$$ppppoooorrrrtttt,,,,$$$$pppprrrroooottttoooo)))) ==== ggggeeeettttsssseeeerrrrvvvv**** (If the entry doesn't exist you get a null list.) Within a scalar context, you get the name, unless the function was a lookup by name, in which case you get the other thing, whatever it is. (If the entry doesn't exist you get the undefined value.) For example: $$$$uuuuiiiidddd ==== ggggeeeettttppppwwwwnnnnaaaammmm $$$$nnnnaaaammmmeeee ==== ggggeeeettttppppwwwwuuuuiiiidddd $$$$nnnnaaaammmmeeee ==== ggggeeeettttppppwwwweeeennnntttt $$$$ggggiiiidddd ==== ggggeeeettttggggrrrrnnnnaaaammmm $$$$nnnnaaaammmmeeee ==== ggggeeeettttggggrrrrggggiiiidddd $$$$nnnnaaaammmmeeee ==== ggggeeeettttggggrrrreeeennnntttt eeeettttcccc.... The $$$$mmmmeeeemmmmbbbbeeeerrrrssss value returned by _g_e_t_g_r_*_(_) is a space separated list of the login names of the members of the group. For the _g_e_t_h_o_s_t_*_(_) functions, if the hhhh____eeeerrrrrrrrnnnnoooo variable is supported in C, it will be returned to you via $$$$???? if the function call fails. The @@@@aaaaddddddddrrrrssss value returned by a successful call is a list of the raw addresses returned by the corresponding system library call. In the Internet domain, each address is four bytes long and you can unpack it by saying something like: (((($$$$aaaa,,,,$$$$bbbb,,,,$$$$cccc,,,,$$$$dddd)))) ==== uuuunnnnppppaaaacccckkkk((((''''CCCC4444'''',,,,$$$$aaaaddddddddrrrr[[[[0000]]]]))));;;; 16/Feb/96 perl 5.002 with 25 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) getsockname SOCKET Returns the packed sockaddr address of this end of the SOCKET connection. uuuusssseeee SSSSoooocccckkkkeeeetttt;;;; $$$$mmmmyyyyssssoooocccckkkkaaaaddddddddrrrr ==== ggggeeeettttssssoooocccckkkknnnnaaaammmmeeee((((SSSSOOOOCCCCKKKK))));;;; (((($$$$ppppoooorrrrtttt,,,, $$$$mmmmyyyyaaaaddddddddrrrr)))) ==== uuuunnnnppppaaaacccckkkk____ssssoooocccckkkkaaaaddddddddrrrr____iiiinnnn(((($$$$mmmmyyyyssssoooocccckkkkaaaaddddddddrrrr))));;;; getsockopt SOCKET,LEVEL,OPTNAME Returns the socket option requested, or undefined if there is an error. glob EXPR Returns the value of EXPR with filename expansions such as a shell would do. This is the internal function implementing the <*.*> operator, except it's easier to use. gmtime EXPR Converts a time as returned by the time function to a 9-element array with the time localized for the standard Greenwich timezone. Typically used as follows: (((($$$$sssseeeecccc,,,,$$$$mmmmiiiinnnn,,,,$$$$hhhhoooouuuurrrr,,,,$$$$mmmmddddaaaayyyy,,,,$$$$mmmmoooonnnn,,,,$$$$yyyyeeeeaaaarrrr,,,,$$$$wwwwddddaaaayyyy,,,,$$$$yyyyddddaaaayyyy,,,,$$$$iiiissssddddsssstttt)))) ==== ggggmmmmttttiiiimmmmeeee((((ttttiiiimmmmeeee))));;;; All array elements are numeric, and come straight out of a struct tm. In particular this means that $$$$mmmmoooonnnn has the range 0..11 and $$$$wwwwddddaaaayyyy has the range 0..6. If EXPR is omitted, does ggggmmmmttttiiiimmmmeeee((((ttttiiiimmmmeeee(((()))))))). goto LABEL goto EXPR goto &NAME The goto-LABEL form finds the statement labeled with LABEL and resumes execution there. It may not be used to go into any construct that requires initialization, such as a subroutine or a foreach loop. It also can't be used to go into a construct that is optimized away. It can be used to go almost anywhere else within the dynamic scope, including out of subroutines, but it's usually better to use some other construct such as last or die. The author of Perl has never felt the need to use this form of goto (in Perl, that is--C is another matter). The goto-EXPR form expects a label name, whose scope will be resolved dynamically. This allows for computed gotos per FORTRAN, but isn't 16/Feb/96 perl 5.002 with 26 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) necessarily recommended if you're optimizing for maintainability: ggggoooottttoooo ((((""""FFFFOOOOOOOO"""",,,, """"BBBBAAAARRRR"""",,,, """"GGGGLLLLAAAARRRRCCCCHHHH""""))))[[[[$$$$iiii]]]];;;; The goto-&NAME form is highly magical, and substitutes a call to the named subroutine for the currently running subroutine. This is used by AUTOLOAD subroutines that wish to load another subroutine and then pretend that the other subroutine had been called in the first place (except that any modifications to @@@@____ in the current subroutine are propagated to the other subroutine.) After the goto, not even _c_a_l_l_e_r_(_) will be able to tell that this routine was called first. grep BLOCK LIST grep EXPR,LIST Evaluates the BLOCK or EXPR for each element of LIST (locally setting $$$$____ to each element) and returns the list value consisting of those elements for which the expression evaluated to TRUE. In a scalar context, returns the number of times the expression was TRUE. @@@@ffffoooooooo ==== ggggrrrreeeepppp((((!!!!////^^^^####////,,,, @@@@bbbbaaaarrrr))));;;; #### wwwweeeeeeeedddd oooouuuutttt ccccoooommmmmmmmeeeennnnttttssss or equivalently, @@@@ffffoooooooo ==== ggggrrrreeeepppp {{{{!!!!////^^^^####////}}}} @@@@bbbbaaaarrrr;;;; #### wwwweeeeeeeedddd oooouuuutttt ccccoooommmmmmmmeeeennnnttttssss Note that, since $$$$____ is a reference into the list value, it can be used to modify the elements of the array. While this is useful and supported, it can cause bizarre results if the LIST is not a named array. hex EXPR Interprets EXPR as a hex string and returns the corresponding decimal value. (To convert strings that might start with 0 or 0x see _o_c_t_(_).) If EXPR is omitted, uses $$$$____. import There is no built-in _i_m_p_o_r_t_(_) function. It is merely an ordinary method (subroutine) defined (or inherited) by modules that wish to export names to another module. The _u_s_e_(_) function calls the _i_m_p_o_r_t_(_) method for the package used. See also the uuuusssseeee entry elsewhere in this documentthe _p_e_r_l_m_o_d manpage, and the _E_x_p_o_r_t_e_r manpage. 16/Feb/96 perl 5.002 with 27 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) index STR,SUBSTR,POSITION index STR,SUBSTR Returns the position of the first occurrence of SUBSTR in STR at or after POSITION. If POSITION is omitted, starts searching from the beginning of the string. The return value is based at 0 (or whatever you've set the $[ variable to--but don't do that). If the substring is not found, returns one less than the base, ordinarily -1. int EXPR Returns the integer portion of EXPR. If EXPR is omitted, uses $$$$____. ioctl FILEHANDLE,FUNCTION,SCALAR Implements the _i_o_c_t_l(2) function. You'll probably have to say rrrreeeeqqqquuuuiiiirrrreeee """"iiiiooooccccttttllll....pppphhhh"""";;;; #### pppprrrroooobbbbaaaabbbbllllyyyy iiiinnnn ////uuuussssrrrr////llllooooccccaaaallll////lllliiiibbbb////ppppeeeerrrrllll////iiiiooooccccttttllll....pppphhhh first to get the correct function definitions. If _i_o_c_t_l_._p_h doesn't exist or doesn't have the correct definitions you'll have to roll your own, based on your C header files such as _<_s_y_s_/_i_o_c_t_l_._h_>. (There is a Perl script called hhhh2222pppphhhh that comes with the Perl kit which may help you in this, but it's non- trivial.) SCALAR will be read and/or written depending on the FUNCTION--a pointer to the string value of SCALAR will be passed as the third argument of the actual ioctl call. (If SCALAR has no string value but does have a numeric value, that value will be passed rather than a pointer to the string value. To guarantee this to be TRUE, add a 0 to the scalar before using it.) The _p_a_c_k_(_) and _u_n_p_a_c_k_(_) functions are useful for manipulating the values of structures used by _i_o_c_t_l_(_). The following example sets the erase character to DEL. rrrreeeeqqqquuuuiiiirrrreeee ''''iiiiooooccccttttllll....pppphhhh'''';;;; $$$$ggggeeeettttpppp ==== &&&&TTTTIIIIOOOOCCCCGGGGEEEETTTTPPPP;;;; ddddiiiieeee """"NNNNOOOO TTTTIIIIOOOOCCCCGGGGEEEETTTTPPPP"""" iiiiffff $$$$@@@@ |||||||| !!!!$$$$ggggeeeettttpppp;;;; $$$$ssssggggttttttttyyyybbbb____tttt ==== """"ccccccccccccccccssss"""";;;; #### 4444 cccchhhhaaaarrrrssss aaaannnndddd aaaa sssshhhhoooorrrrtttt iiiiffff ((((iiiiooooccccttttllll((((SSSSTTTTDDDDIIIINNNN,,,,$$$$ggggeeeettttpppp,,,,$$$$ssssggggttttttttyyyybbbb)))))))) {{{{ @@@@aaaarrrryyyy ==== uuuunnnnppppaaaacccckkkk(((($$$$ssssggggttttttttyyyybbbb____tttt,,,,$$$$ssssggggttttttttyyyybbbb))));;;; $$$$aaaarrrryyyy[[[[2222]]]] ==== 111122227777;;;; $$$$ssssggggttttttttyyyybbbb ==== ppppaaaacccckkkk(((($$$$ssssggggttttttttyyyybbbb____tttt,,,,@@@@aaaarrrryyyy))));;;; iiiiooooccccttttllll((((SSSSTTTTDDDDIIIINNNN,,,,&&&&TTTTIIIIOOOOCCCCSSSSEEEETTTTPPPP,,,,$$$$ssssggggttttttttyyyybbbb)))) |||||||| ddddiiiieeee """"CCCCaaaannnn''''tttt iiiiooooccccttttllll:::: $$$$!!!!"""";;;; }}}} The return value of ioctl (and fcntl) is as follows: 16/Feb/96 perl 5.002 with 28 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) iiiiffff OOOOSSSS rrrreeeettttuuuurrrrnnnnssss:::: tttthhhheeeennnn PPPPeeeerrrrllll rrrreeeettttuuuurrrrnnnnssss:::: ----1111 uuuunnnnddddeeeeffffiiiinnnneeeedddd vvvvaaaalllluuuueeee 0000 ssssttttrrrriiiinnnngggg """"0000 bbbbuuuutttt ttttrrrruuuueeee"""" aaaannnnyyyytttthhhhiiiinnnngggg eeeellllsssseeee tttthhhhaaaatttt nnnnuuuummmmbbbbeeeerrrr Thus Perl returns TRUE on success and FALSE on failure, yet you can still easily determine the actual value returned by the operating system: (((($$$$rrrreeeettttvvvvaaaallll ==== iiiiooooccccttttllll((((............)))))))) |||||||| (((($$$$rrrreeeettttvvvvaaaallll ==== ----1111))));;;; pppprrrriiiinnnnttttffff """"SSSSyyyysssstttteeeemmmm rrrreeeettttuuuurrrrnnnneeeedddd %%%%dddd\\\\nnnn"""",,,, $$$$rrrreeeettttvvvvaaaallll;;;; join EXPR,LIST Joins the separate strings of LIST or ARRAY into a single string with fields separated by the value of EXPR, and returns the string. Example: $$$$____ ==== jjjjooooiiiinnnn((((''''::::'''',,,, $$$$llllooooggggiiiinnnn,,,,$$$$ppppaaaasssssssswwwwdddd,,,,$$$$uuuuiiiidddd,,,,$$$$ggggiiiidddd,,,,$$$$ggggccccoooossss,,,,$$$$hhhhoooommmmeeee,,,,$$$$sssshhhheeeellllllll))));;;; See the sssspppplllliiiitttt entry in the _p_e_r_l_f_u_n_c manpage. keys ASSOC_ARRAY Returns a normal array consisting of all the keys of the named associative array. (In a scalar context, returns the number of keys.) The keys are returned in an apparently random order, but it is the same order as either the _v_a_l_u_e_s_(_) or _e_a_c_h_(_) function produces (given that the associative array has not been modified). Here is yet another way to print your environment: @@@@kkkkeeeeyyyyssss ==== kkkkeeeeyyyyssss %%%%EEEENNNNVVVV;;;; @@@@vvvvaaaalllluuuueeeessss ==== vvvvaaaalllluuuueeeessss %%%%EEEENNNNVVVV;;;; wwwwhhhhiiiilllleeee (((($$$$####kkkkeeeeyyyyssss >>>>==== 0000)))) {{{{ pppprrrriiiinnnntttt ppppoooopppp((((@@@@kkkkeeeeyyyyssss)))),,,, ''''===='''',,,, ppppoooopppp((((@@@@vvvvaaaalllluuuueeeessss)))),,,, """"\\\\nnnn"""";;;; }}}} or how about sorted by key: ffffoooorrrreeeeaaaacccchhhh $$$$kkkkeeeeyyyy ((((ssssoooorrrrtttt((((kkkkeeeeyyyyssss %%%%EEEENNNNVVVV)))))))) {{{{ pppprrrriiiinnnntttt $$$$kkkkeeeeyyyy,,,, ''''===='''',,,, $$$$EEEENNNNVVVV{{{{$$$$kkkkeeeeyyyy}}}},,,, """"\\\\nnnn"""";;;; }}}} To sort an array by value, you'll need to use a ssssoooorrrrtttt{{{{}}}} function. Here's a descending numeric sort of a hash by its values: ffffoooorrrreeeeaaaacccchhhh $$$$kkkkeeeeyyyy ((((ssssoooorrrrtttt {{{{ $$$$hhhhaaaasssshhhh{{{{$$$$bbbb}}}} <<<<====>>>> $$$$hhhhaaaasssshhhh{{{{$$$$aaaa}}}} }}}} kkkkeeeeyyyyssss %%%%hhhhaaaasssshhhh)))))))) {{{{ pppprrrriiiinnnnttttffff """"%%%%4444dddd %%%%ssss\\\\nnnn"""",,,, $$$$hhhhaaaasssshhhh{{{{$$$$kkkkeeeeyyyy}}}},,,, $$$$kkkkeeeeyyyy;;;; }}}} 16/Feb/96 perl 5.002 with 29 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) kill LIST Sends a signal to a list of processes. The first element of the list must be the signal to send. Returns the number of processes successfully signaled. $$$$ccccnnnntttt ==== kkkkiiiillllllll 1111,,,, $$$$cccchhhhiiiilllldddd1111,,,, $$$$cccchhhhiiiilllldddd2222;;;; kkkkiiiillllllll 9999,,,, @@@@ggggoooonnnneeeerrrrssss;;;; Unlike in the shell, in Perl if the _S_I_G_N_A_L is negative, it kills process groups instead of processes. (On System V, a negative _P_R_O_C_E_S_S number will also kill process groups, but that's not portable.) That means you usually want to use positive not negative signals. You may also use a signal name in quotes. See the the section on _S_i_g_n_a_l_s in the _p_e_r_l_i_p_c manpage man page for details. last LABEL last The llllaaaasssstttt command is like the bbbbrrrreeeeaaaakkkk statement in C (as used in loops); it immediately exits the loop in question. If the LABEL is omitted, the command refers to the innermost enclosing loop. The ccccoooonnnnttttiiiinnnnuuuueeee block, if any, is not executed: LLLLIIIINNNNEEEE:::: wwwwhhhhiiiilllleeee ((((<<<<SSSSTTTTDDDDIIIINNNN>>>>)))) {{{{ llllaaaasssstttt LLLLIIIINNNNEEEE iiiiffff ////^^^^$$$$////;;;; #### eeeexxxxiiiitttt wwwwhhhheeeennnn ddddoooonnnneeee wwwwiiiitttthhhh hhhheeeeaaaaddddeeeerrrr ............ }}}} lc EXPR Returns an lowercased version of EXPR. This is the internal function implementing the \L escape in double-quoted strings. Should respect any POSIX _s_e_t_l_o_c_a_l_e_(_) settings. lcfirst EXPR Returns the value of EXPR with the first character lowercased. This is the internal function implementing the \l escape in double-quoted strings. Should respect any POSIX _s_e_t_l_o_c_a_l_e_(_) settings. length EXPR Returns the length in characters of the value of EXPR. If EXPR is omitted, returns length of $$$$____. link OLDFILE,NEWFILE Creates a new filename linked to the old filename. Returns 1 for success, 0 otherwise. 16/Feb/96 perl 5.002 with 30 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) listen SOCKET,QUEUESIZE Does the same thing that the listen system call does. Returns TRUE if it succeeded, FALSE otherwise. See example in the section on _S_o_c_k_e_t_s_: _C_l_i_e_n_t_/_S_e_r_v_e_r _C_o_m_m_u_n_i_c_a_t_i_o_n in the _p_e_r_l_i_p_c manpage. local EXPR A local modifies the listed variables to be local to the enclosing block, subroutine, eeeevvvvaaaallll{{{{}}}} or ddddoooo. If more than one value is listed, the list must be placed in parens. See L<perlsub/"Temporary Values via local()"> for details. But you really probably want to be using _m_y_(_) instead, because _l_o_c_a_l_(_) isn't what most people think of as "local"). See L<perlsub/"Private Variables via my()"> for details. localtime EXPR Converts a time as returned by the time function to a 9-element array with the time analyzed for the local timezone. Typically used as follows: (((($$$$sssseeeecccc,,,,$$$$mmmmiiiinnnn,,,,$$$$hhhhoooouuuurrrr,,,,$$$$mmmmddddaaaayyyy,,,,$$$$mmmmoooonnnn,,,,$$$$yyyyeeeeaaaarrrr,,,,$$$$wwwwddddaaaayyyy,,,,$$$$yyyyddddaaaayyyy,,,,$$$$iiiissssddddsssstttt)))) ==== llllooooccccaaaallllttttiiiimmmmeeee((((ttttiiiimmmmeeee))));;;; All array elements are numeric, and come straight out of a struct tm. In particular this means that $$$$mmmmoooonnnn has the range 0..11 and $$$$wwwwddddaaaayyyy has the range 0..6. If EXPR is omitted, does _l_o_c_a_l_t_i_m_e(time). In a scalar context, prints out the _c_t_i_m_e(3) value: $$$$nnnnoooowwww____ssssttttrrrriiiinnnngggg ==== llllooooccccaaaallllttttiiiimmmmeeee;;;; #### eeee....gggg.... """"TTTThhhhuuuu OOOOcccctttt 11113333 00004444::::55554444::::33334444 1111999999994444"""" See also the ttttiiiimmmmeeeellllooooccccaaaallll entry in the _p_e_r_l_m_o_d manpage and the _s_t_r_f_t_i_m_e(3) function available via the POSIX modulie. log EXPR Returns logarithm (base _e) of EXPR. If EXPR is omitted, returns log of $$$$____. lstat FILEHANDLE lstat EXPR Does the same thing as the _s_t_a_t_(_) function, but stats a symbolic link instead of the file the symbolic link points to. If symbolic links are unimplemented on your system, a normal _s_t_a_t_(_) is done. 16/Feb/96 perl 5.002 with 31 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) m// The match operator. See the _p_e_r_l_o_p manpage. map BLOCK LIST map EXPR,LIST Evaluates the BLOCK or EXPR for each element of LIST (locally setting $$$$____ to each element) and returns the list value composed of the results of each such evaluation. Evaluates BLOCK or EXPR in a list context, so each element of LIST may produce zero, one, or more elements in the returned value. @@@@cccchhhhaaaarrrrssss ==== mmmmaaaapppp((((cccchhhhrrrr,,,, @@@@nnnnuuuummmmssss))));;;; translates a list of numbers to the corresponding characters. And %%%%hhhhaaaasssshhhh ==== mmmmaaaapppp {{{{ ggggeeeettttkkkkeeeeyyyy(((($$$$____)))) ====>>>> $$$$____ }}}} @@@@aaaarrrrrrrraaaayyyy;;;; is just a funny way to write %%%%hhhhaaaasssshhhh ==== (((())));;;; ffffoooorrrreeeeaaaacccchhhh $$$$____ ((((@@@@aaaarrrrrrrraaaayyyy)))) {{{{ $$$$hhhhaaaasssshhhh{{{{ggggeeeettttkkkkeeeeyyyy(((($$$$____))))}}}} ==== $$$$____;;;; }}}} mkdir FILENAME,MODE Creates the directory specified by FILENAME, with permissions specified by MODE (as modified by umask). If it succeeds it returns 1, otherwise it returns 0 and sets $! (errno). msgctl ID,CMD,ARG Calls the System V IPC function _m_s_g_c_t_l(2). If CMD is &IPC_STAT, then ARG must be a variable which will hold the returned msqid_ds structure. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise. msgget KEY,FLAGS Calls the System V IPC function _m_s_g_g_e_t(2). Returns the message queue id, or the undefined value if there is an error. msgsnd ID,MSG,FLAGS Calls the System V IPC function msgsnd to send the message MSG to the message queue ID. MSG must begin with the long integer message type, which may be created with ppppaaaacccckkkk((((""""llll"""",,,, $$$$ttttyyyyppppeeee)))). Returns TRUE if successful, or FALSE if there is an error. 16/Feb/96 perl 5.002 with 32 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) msgrcv ID,VAR,SIZE,TYPE,FLAGS Calls the System V IPC function msgrcv to receive a message from message queue ID into variable VAR with a maximum message size of SIZE. Note that if a message is received, the message type will be the first thing in VAR, and the maximum length of VAR is SIZE plus the size of the message type. Returns TRUE if successful, or FALSE if there is an error. my EXPR A "my" declares the listed variables to be local (lexically) to the enclosing block, subroutine, eeeevvvvaaaallll, or ddddoooo////rrrreeeeqqqquuuuiiiirrrreeee////uuuusssseeee'd file. If more than one value is listed, the list must be placed in parens. See the section on _P_r_i_v_a_t_e _V_a_r_i_a_b_l_e_s _v_i_a _m_y_(_) in the _p_e_r_l_s_u_b manpage for details. next LABEL next The nnnneeeexxxxtttt command is like the ccccoooonnnnttttiiiinnnnuuuueeee statement in C; it starts the next iteration of the loop: LLLLIIIINNNNEEEE:::: wwwwhhhhiiiilllleeee ((((<<<<SSSSTTTTDDDDIIIINNNN>>>>)))) {{{{ nnnneeeexxxxtttt LLLLIIIINNNNEEEE iiiiffff ////^^^^####////;;;; #### ddddiiiissssccccaaaarrrrdddd ccccoooommmmmmmmeeeennnnttttssss ............ }}}} Note that if there were a ccccoooonnnnttttiiiinnnnuuuueeee block on the above, it would get executed even on discarded lines. If the LABEL is omitted, the command refers to the innermost enclosing loop. no Module LIST See the "use" function, which "no" is the opposite of. oct EXPR Interprets EXPR as an octal string and returns the corresponding decimal value. (If EXPR happens to start off with 0x, interprets it as a hex string instead.) The following will handle decimal, octal, and hex in the standard Perl or C notation: $$$$vvvvaaaallll ==== oooocccctttt(((($$$$vvvvaaaallll)))) iiiiffff $$$$vvvvaaaallll ====~~~~ ////^^^^0000////;;;; If EXPR is omitted, uses $$$$____. open FILEHANDLE,EXPR open FILEHANDLE Opens the file whose filename is given by EXPR, and associates it with FILEHANDLE. If FILEHANDLE is an expression, its value is used as the name of the real filehandle wanted. If EXPR is omitted, 16/Feb/96 perl 5.002 with 33 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) the scalar variable of the same name as the FILEHANDLE contains the filename. If the filename begins with "<" or nothing, the file is opened for input. If the filename begins with ">", the file is opened for output. If the filename begins with ">>", the file is opened for appending. You can put a '+' in front of the '>' or '<' to indicate that you want both read and write access to the file; thus '+<' is usually preferred for read/write updates--the '+>' mode would clobber the file first. These correspond to the _f_o_p_e_n(3) modes of 'r', 'r+', 'w', 'w+', 'a', and 'a+'. If the filename begins with "|", the filename is interpreted as a command to which output is to be piped, and if the filename ends with a "|", the filename is interpreted See the section on _U_s_i_n_g _o_p_e_n_(_) _f_o_r _I_P_C in the _p_e_r_l_i_p_c manpage for more examples of this. as command which pipes input to us. (You may not have a raw _o_p_e_n_(_) to a command that pipes both in _a_n_d out, but see See the _o_p_e_n_2 manpage, the _o_p_e_n_3 manpage, and the section on _B_i_d_i_r_e_c_t_i_o_n_a_l _C_o_m_m_u_n_i_c_a_t_i_o_n in the _p_e_r_l_i_p_c manpage for alternatives.) Opening '-' opens STDIN and opening '>-' opens STDOUT. Open returns non-zero upon success, the undefined value otherwise. If the open involved a pipe, the return value happens to be the pid of the subprocess. If you're unfortunate enough to be running Perl on a system that distinguishes between text files and binary files (modern operating systems don't care), then you should check out the bbbbiiiinnnnmmmmooooddddeeee entry elsewhere in this documentfor tips for dealing with this. The key distinction between systems that need binmode and those that don't is their text file formats. Systems like Unix and Plan9 that delimit lines with a single character, and that encode that character in C as '\n', do not need bbbbiiiinnnnmmmmooooddddeeee. The rest need it. Examples: $$$$AAAARRRRTTTTIIIICCCCLLLLEEEE ==== 111100000000;;;; ooooppppeeeennnn AAAARRRRTTTTIIIICCCCLLLLEEEE oooorrrr ddddiiiieeee """"CCCCaaaannnn''''tttt ffffiiiinnnndddd aaaarrrrttttiiiicccclllleeee $$$$AAAARRRRTTTTIIIICCCCLLLLEEEE:::: $$$$!!!!\\\\nnnn"""";;;; wwwwhhhhiiiilllleeee ((((<<<<AAAARRRRTTTTIIIICCCCLLLLEEEE>>>>)))) {{{{............ ooooppppeeeennnn((((LLLLOOOOGGGG,,,, ''''>>>>>>>>////uuuussssrrrr////ssssppppoooooooollll////nnnneeeewwwwssss////ttttwwwwiiiittttlllloooogggg''''))));;;; #### ((((lllloooogggg iiiissss rrrreeeesssseeeerrrrvvvveeeedddd)))) ooooppppeeeennnn((((DDDDBBBBAAAASSSSEEEE,,,, ''''++++<<<<ddddbbbbaaaasssseeee....mmmmiiiinnnneeee''''))));;;; #### ooooppppeeeennnn ffffoooorrrr uuuuppppddddaaaatttteeee ooooppppeeeennnn((((AAAARRRRTTTTIIIICCCCLLLLEEEE,,,, """"ccccaaaaeeeessssaaaarrrr <<<<$$$$aaaarrrrttttiiiicccclllleeee ||||""""))));;;; #### ddddeeeeccccrrrryyyypppptttt aaaarrrrttttiiiicccclllleeee 16/Feb/96 perl 5.002 with 34 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ooooppppeeeennnn((((EEEEXXXXTTTTRRRRAAAACCCCTTTT,,,, """"||||ssssoooorrrrtttt >>>>////ttttmmmmpppp////TTTTmmmmpppp$$$$$$$$""""))));;;; #### $$$$$$$$ iiiissss oooouuuurrrr pppprrrroooocccceeeessssssss iiiidddd #### pppprrrroooocccceeeessssssss aaaarrrrgggguuuummmmeeeennnntttt lllliiiisssstttt ooooffff ffffiiiilllleeeessss aaaalllloooonnnngggg wwwwiiiitttthhhh aaaannnnyyyy iiiinnnncccclllluuuuddddeeeessss ffffoooorrrreeeeaaaacccchhhh $$$$ffffiiiilllleeee ((((@@@@AAAARRRRGGGGVVVV)))) {{{{ pppprrrroooocccceeeessssssss(((($$$$ffffiiiilllleeee,,,, ''''ffffhhhh00000000''''))));;;; }}}} ssssuuuubbbb pppprrrroooocccceeeessssssss {{{{ llllooooccccaaaallll(((($$$$ffffiiiilllleeeennnnaaaammmmeeee,,,, $$$$iiiinnnnppppuuuutttt)))) ==== @@@@____;;;; $$$$iiiinnnnppppuuuutttt++++++++;;;; #### tttthhhhiiiissss iiiissss aaaa ssssttttrrrriiiinnnngggg iiiinnnnccccrrrreeeemmmmeeeennnntttt uuuunnnnlllleeeessssssss ((((ooooppppeeeennnn(((($$$$iiiinnnnppppuuuutttt,,,, $$$$ffffiiiilllleeeennnnaaaammmmeeee)))))))) {{{{ pppprrrriiiinnnntttt SSSSTTTTDDDDEEEERRRRRRRR """"CCCCaaaannnn''''tttt ooooppppeeeennnn $$$$ffffiiiilllleeeennnnaaaammmmeeee:::: $$$$!!!!\\\\nnnn"""";;;; rrrreeeettttuuuurrrrnnnn;;;; }}}} wwwwhhhhiiiilllleeee ((((<<<<$$$$iiiinnnnppppuuuutttt>>>>)))) {{{{ #### nnnnooootttteeee uuuusssseeee ooooffff iiiinnnnddddiiiirrrreeeeccccttttiiiioooonnnn iiiiffff ((((////^^^^####iiiinnnncccclllluuuuddddeeee """"((((....****))))""""////)))) {{{{ pppprrrroooocccceeeessssssss(((($$$$1111,,,, $$$$iiiinnnnppppuuuutttt))));;;; nnnneeeexxxxtttt;;;; }}}} ............ #### wwwwhhhhaaaatttteeeevvvveeeerrrr }}}} }}}} You may also, in the Bourne shell tradition, specify an EXPR beginning with ">&", in which case the rest of the string is interpreted as the name of a filehandle (or file descriptor, if numeric) which is to be duped and opened. You may use & after >, >>, <, +>, +>> and +<. The mode you specify should match the mode of the original filehandle. (Duping a filehandle does not take into acount any existing contents of stdio buffers.) Here is a script that saves, redirects, and restores STDOUT and STDERR: ####!!!!////uuuussssrrrr////bbbbiiiinnnn////ppppeeeerrrrllll ooooppppeeeennnn((((SSSSAAAAVVVVEEEEOOOOUUUUTTTT,,,, """">>>>&&&&SSSSTTTTDDDDOOOOUUUUTTTT""""))));;;; ooooppppeeeennnn((((SSSSAAAAVVVVEEEEEEEERRRRRRRR,,,, """">>>>&&&&SSSSTTTTDDDDEEEERRRRRRRR""""))));;;; ooooppppeeeennnn((((SSSSTTTTDDDDOOOOUUUUTTTT,,,, """">>>>ffffoooooooo....oooouuuutttt"""")))) |||||||| ddddiiiieeee """"CCCCaaaannnn''''tttt rrrreeeeddddiiiirrrreeeecccctttt ssssttttddddoooouuuutttt"""";;;; ooooppppeeeennnn((((SSSSTTTTDDDDEEEERRRRRRRR,,,, """">>>>&&&&SSSSTTTTDDDDOOOOUUUUTTTT"""")))) |||||||| ddddiiiieeee """"CCCCaaaannnn''''tttt dddduuuupppp ssssttttddddoooouuuutttt"""";;;; sssseeeelllleeeecccctttt((((SSSSTTTTDDDDEEEERRRRRRRR))));;;; $$$$|||| ==== 1111;;;; #### mmmmaaaakkkkeeee uuuunnnnbbbbuuuuffffffffeeeerrrreeeedddd sssseeeelllleeeecccctttt((((SSSSTTTTDDDDOOOOUUUUTTTT))));;;; $$$$|||| ==== 1111;;;; #### mmmmaaaakkkkeeee uuuunnnnbbbbuuuuffffffffeeeerrrreeeedddd pppprrrriiiinnnntttt SSSSTTTTDDDDOOOOUUUUTTTT """"ssssttttddddoooouuuutttt 1111\\\\nnnn"""";;;; #### tttthhhhiiiissss wwwwoooorrrrkkkkssss ffffoooorrrr pppprrrriiiinnnntttt SSSSTTTTDDDDEEEERRRRRRRR """"ssssttttddddeeeerrrrrrrr 1111\\\\nnnn"""";;;; #### ssssuuuubbbbpppprrrroooocccceeeesssssssseeeessss ttttoooooooo cccclllloooosssseeee((((SSSSTTTTDDDDOOOOUUUUTTTT))));;;; cccclllloooosssseeee((((SSSSTTTTDDDDEEEERRRRRRRR))));;;; 16/Feb/96 perl 5.002 with 35 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ooooppppeeeennnn((((SSSSTTTTDDDDOOOOUUUUTTTT,,,, """">>>>&&&&SSSSAAAAVVVVEEEEOOOOUUUUTTTT""""))));;;; ooooppppeeeennnn((((SSSSTTTTDDDDEEEERRRRRRRR,,,, """">>>>&&&&SSSSAAAAVVVVEEEEEEEERRRRRRRR""""))));;;; pppprrrriiiinnnntttt SSSSTTTTDDDDOOOOUUUUTTTT """"ssssttttddddoooouuuutttt 2222\\\\nnnn"""";;;; pppprrrriiiinnnntttt SSSSTTTTDDDDEEEERRRRRRRR """"ssssttttddddeeeerrrrrrrr 2222\\\\nnnn"""";;;; If you specify "<&=N", where N is a number, then Perl will do an equivalent of C's _f_d_o_p_e_n_(_) of that file descriptor; this is more parsimonious of file descriptors. For example: ooooppppeeeennnn((((FFFFIIIILLLLEEEEHHHHAAAANNNNDDDDLLLLEEEE,,,, """"<<<<&&&&====$$$$ffffdddd"""")))) If you open a pipe on the command "-", i.e. either "|-" or "-|", then there is an implicit fork done, and the return value of open is the pid of the child within the parent process, and 0 within the child process. (Use _d_e_f_i_n_e_d($pid) to determine whether the open was successful.) The filehandle behaves normally for the parent, but i/o to that filehandle is piped from/to the STDOUT/STDIN of the child process. In the child process the filehandle isn't opened--i/o happens from/to the new STDOUT or STDIN. Typically this is used like the normal piped open when you want to exercise more control over just how the pipe command gets executed, such as when you are running setuid, and don't want to have to scan shell commands for metacharacters. The following pairs are more or less equivalent: ooooppppeeeennnn((((FFFFOOOOOOOO,,,, """"||||ttttrrrr ''''[[[[aaaa----zzzz]]]]'''' ''''[[[[AAAA----ZZZZ]]]]''''""""))));;;; ooooppppeeeennnn((((FFFFOOOOOOOO,,,, """"||||----"""")))) |||||||| eeeexxxxeeeecccc ''''ttttrrrr'''',,,, ''''[[[[aaaa----zzzz]]]]'''',,,, ''''[[[[AAAA----ZZZZ]]]]'''';;;; ooooppppeeeennnn((((FFFFOOOOOOOO,,,, """"ccccaaaatttt ----nnnn ''''$$$$ffffiiiilllleeee''''||||""""))));;;; ooooppppeeeennnn((((FFFFOOOOOOOO,,,, """"----||||"""")))) |||||||| eeeexxxxeeeecccc ''''ccccaaaatttt'''',,,, ''''----nnnn'''',,,, $$$$ffffiiiilllleeee;;;; See the section on _S_a_f_e _P_i_p_e _O_p_e_n_s in the _p_e_r_l_i_p_c manpage for more examples of this. Explicitly closing any piped filehandle causes the parent process to wait for the child to finish, and returns the status value in $?. Note: on any operation which may do a fork, unflushed buffers remain unflushed in both processes, which means you may need to set $| to avoid duplicate output. Using the FileHandle constructor from the FileHandle package, you can generate anonymous filehandles which have the scope of whatever variables hold references to them, and automatically close whenever and however you leave that scope: 16/Feb/96 perl 5.002 with 36 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) uuuusssseeee FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee;;;; ............ ssssuuuubbbb rrrreeeeaaaadddd____mmmmyyyyffffiiiilllleeee____mmmmuuuunnnnggggeeeedddd {{{{ mmmmyyyy $$$$AAAALLLLLLLL ==== sssshhhhiiiifffftttt;;;; mmmmyyyy $$$$hhhhaaaannnnddddlllleeee ==== nnnneeeewwww FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee;;;; ooooppppeeeennnn(((($$$$hhhhaaaannnnddddlllleeee,,,, """"mmmmyyyyffffiiiilllleeee"""")))) oooorrrr ddddiiiieeee """"mmmmyyyyffffiiiilllleeee:::: $$$$!!!!"""";;;; $$$$ffffiiiirrrrsssstttt ==== <<<<$$$$hhhhaaaannnnddddlllleeee>>>> oooorrrr rrrreeeettttuuuurrrrnnnn (((())));;;; #### AAAAuuuuttttoooommmmaaaattttiiiiccccaaaallllllllyyyy cccclllloooosssseeeedddd hhhheeeerrrreeee.... mmmmuuuunnnngggg $$$$ffffiiiirrrrsssstttt oooorrrr ddddiiiieeee """"mmmmuuuunnnngggg ffffaaaaiiiilllleeeedddd"""";;;; #### OOOOrrrr hhhheeeerrrreeee.... rrrreeeettttuuuurrrrnnnn $$$$ffffiiiirrrrsssstttt,,,, <<<<$$$$hhhhaaaannnnddddlllleeee>>>> iiiiffff $$$$AAAALLLLLLLL;;;; #### OOOOrrrr hhhheeeerrrreeee.... $$$$ffffiiiirrrrsssstttt;;;; #### OOOOrrrr hhhheeeerrrreeee.... }}}} The filename that is passed to open will have leading and trailing whitespace deleted. In order to open a file with arbitrary weird characters in it, it's necessary to protect any leading and trailing whitespace thusly: $$$$ffffiiiilllleeee ====~~~~ ssss####^^^^((((\\\\ssss))))####....////$$$$1111####;;;; ooooppppeeeennnn((((FFFFOOOOOOOO,,,, """"<<<< $$$$ffffiiiilllleeee\\\\0000""""))));;;; If you want a "real" C _o_p_e_n_(_) (see the _o_p_e_n_(_2_) manpage on your system), then you should use the _s_y_s_o_p_e_n_(_) function. This is another way to protect your filenames from interpretation. For example: uuuusssseeee FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee;;;; ssssyyyyssssooooppppeeeennnn((((HHHHAAAANNNNDDDDLLLLEEEE,,,, $$$$ppppaaaatttthhhh,,,, OOOO____RRRRDDDDWWWWRRRR||||OOOO____CCCCRRRREEEEAAAATTTT||||OOOO____EEEEXXXXCCCCLLLL,,,, 0000777700000000)))) oooorrrr ddddiiiieeee """"ssssyyyyssssooooppppeeeennnn $$$$ppppaaaatttthhhh:::: $$$$!!!!"""";;;; HHHHAAAANNNNDDDDLLLLEEEE---->>>>aaaauuuuttttoooofffflllluuuusssshhhh((((1111))));;;; HHHHAAAANNNNDDDDLLLLEEEE---->>>>pppprrrriiiinnnntttt((((""""ssssttttuuuuffffffff $$$$$$$$\\\\nnnn""""))));;;; sssseeeeeeeekkkk((((HHHHAAAANNNNDDDDLLLLEEEE,,,, 0000,,,, 0000))));;;; pppprrrriiiinnnntttt """"FFFFiiiilllleeee ccccoooonnnnttttaaaaiiiinnnnssss:::: """",,,, <<<<HHHHAAAANNNNDDDDLLLLEEEE>>>>;;;; See the sssseeeeeeeekkkk(((()))) entry elsewhere in this documentfor some details about mixing reading and writing. opendir DIRHANDLE,EXPR Opens a directory named EXPR for processing by _r_e_a_d_d_i_r_(_), _t_e_l_l_d_i_r_(_), _s_e_e_k_d_i_r_(_), _r_e_w_i_n_d_d_i_r_(_) and _c_l_o_s_e_d_i_r_(_). Returns TRUE if successful. DIRHANDLEs have their own namespace separate from FILEHANDLEs. ord EXPR Returns the numeric ascii value of the first character of EXPR. If EXPR is omitted, uses $$$$____. pack TEMPLATE,LIST Takes an array or list of values and packs it into a binary structure, returning the string containing the structure. The TEMPLATE is a 16/Feb/96 perl 5.002 with 37 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) sequence of characters that give the order and type of values, as follows: AAAA AAAAnnnn aaaasssscccciiiiiiii ssssttttrrrriiiinnnngggg,,,, wwwwiiiillllllll bbbbeeee ssssppppaaaacccceeee ppppaaaaddddddddeeeedddd.... aaaa AAAAnnnn aaaasssscccciiiiiiii ssssttttrrrriiiinnnngggg,,,, wwwwiiiillllllll bbbbeeee nnnnuuuullllllll ppppaaaaddddddddeeeedddd.... bbbb AAAA bbbbiiiitttt ssssttttrrrriiiinnnngggg ((((aaaasssscccceeeennnnddddiiiinnnngggg bbbbiiiitttt oooorrrrddddeeeerrrr,,,, lllliiiikkkkeeee vvvveeeecccc(((()))))))).... BBBB AAAA bbbbiiiitttt ssssttttrrrriiiinnnngggg ((((ddddeeeesssscccceeeennnnddddiiiinnnngggg bbbbiiiitttt oooorrrrddddeeeerrrr)))).... hhhh AAAA hhhheeeexxxx ssssttttrrrriiiinnnngggg ((((lllloooowwww nnnnyyyybbbbbbbblllleeee ffffiiiirrrrsssstttt)))).... HHHH AAAA hhhheeeexxxx ssssttttrrrriiiinnnngggg ((((hhhhiiiigggghhhh nnnnyyyybbbbbbbblllleeee ffffiiiirrrrsssstttt)))).... cccc AAAA ssssiiiiggggnnnneeeedddd cccchhhhaaaarrrr vvvvaaaalllluuuueeee.... CCCC AAAAnnnn uuuunnnnssssiiiiggggnnnneeeedddd cccchhhhaaaarrrr vvvvaaaalllluuuueeee.... ssss AAAA ssssiiiiggggnnnneeeedddd sssshhhhoooorrrrtttt vvvvaaaalllluuuueeee.... SSSS AAAAnnnn uuuunnnnssssiiiiggggnnnneeeedddd sssshhhhoooorrrrtttt vvvvaaaalllluuuueeee.... iiii AAAA ssssiiiiggggnnnneeeedddd iiiinnnntttteeeeggggeeeerrrr vvvvaaaalllluuuueeee.... IIII AAAAnnnn uuuunnnnssssiiiiggggnnnneeeedddd iiiinnnntttteeeeggggeeeerrrr vvvvaaaalllluuuueeee.... llll AAAA ssssiiiiggggnnnneeeedddd lllloooonnnngggg vvvvaaaalllluuuueeee.... LLLL AAAAnnnn uuuunnnnssssiiiiggggnnnneeeedddd lllloooonnnngggg vvvvaaaalllluuuueeee.... nnnn AAAA sssshhhhoooorrrrtttt iiiinnnn """"nnnneeeettttwwwwoooorrrrkkkk"""" oooorrrrddddeeeerrrr.... NNNN AAAA lllloooonnnngggg iiiinnnn """"nnnneeeettttwwwwoooorrrrkkkk"""" oooorrrrddddeeeerrrr.... vvvv AAAA sssshhhhoooorrrrtttt iiiinnnn """"VVVVAAAAXXXX"""" ((((lllliiiittttttttlllleeee----eeeennnnddddiiiiaaaannnn)))) oooorrrrddddeeeerrrr.... VVVV AAAA lllloooonnnngggg iiiinnnn """"VVVVAAAAXXXX"""" ((((lllliiiittttttttlllleeee----eeeennnnddddiiiiaaaannnn)))) oooorrrrddddeeeerrrr.... ffff AAAA ssssiiiinnnngggglllleeee----pppprrrreeeecccciiiissssiiiioooonnnn ffffllllooooaaaatttt iiiinnnn tttthhhheeee nnnnaaaattttiiiivvvveeee ffffoooorrrrmmmmaaaatttt.... dddd AAAA ddddoooouuuubbbblllleeee----pppprrrreeeecccciiiissssiiiioooonnnn ffffllllooooaaaatttt iiiinnnn tttthhhheeee nnnnaaaattttiiiivvvveeee ffffoooorrrrmmmmaaaatttt.... pppp AAAA ppppooooiiiinnnntttteeeerrrr ttttoooo aaaa nnnnuuuullllllll----tttteeeerrrrmmmmiiiinnnnaaaatttteeeedddd ssssttttrrrriiiinnnngggg.... PPPP AAAA ppppooooiiiinnnntttteeeerrrr ttttoooo aaaa ssssttttrrrruuuuccccttttuuuurrrreeee ((((ffffiiiixxxxeeeedddd----lllleeeennnnggggtttthhhh ssssttttrrrriiiinnnngggg)))).... uuuu AAAA uuuuuuuueeeennnnccccooooddddeeeedddd ssssttttrrrriiiinnnngggg.... xxxx AAAA nnnnuuuullllllll bbbbyyyytttteeee.... XXXX BBBBaaaacccckkkk uuuupppp aaaa bbbbyyyytttteeee.... @@@@ NNNNuuuullllllll ffffiiiillllllll ttttoooo aaaabbbbssssoooolllluuuutttteeee ppppoooossssiiiittttiiiioooonnnn.... Each letter may optionally be followed by a number which gives a repeat count. With all types except "a", "A", "b", "B", "h" and "H", and "P" the pack function will gobble up that many values from the LIST. A * for the repeat count means to use however many items are left. The "a" and "A" types gobble just one value, but pack it as a string of length count, padding with nulls or spaces as necessary. (When unpacking, "A" strips trailing spaces and nulls, but "a" does not.) Likewise, the "b" and "B" fields pack a string that many bits long. The "h" and "H" fields pack a string that many nybbles long. The "P" packs a pointer to a structure of the size indicated by the length. Real numbers (floats and doubles) are in the native machine format only; due to the multiplicity of floating formats around, and the lack of a standard "network" representation, no 16/Feb/96 perl 5.002 with 38 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) facility for interchange has been made. This means that packed floating point data written on one machine may not be readable on another - even if both use IEEE floating point arithmetic (as the endian-ness of the memory representation is not part of the IEEE spec). Note that Perl uses doubles internally for all numeric calculation, and converting from double into float and thence back to double again will lose precision (i.e. uuuunnnnppppaaaacccckkkk((((""""ffff"""",,,, ppppaaaacccckkkk((((""""ffff"""",,,, $$$$ffffoooooooo))))) will not in general equal $$$$ffffoooooooo). Examples: $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""cccccccccccccccc"""",,,,66665555,,,,66666666,,,,66667777,,,,66668888))));;;; #### ffffoooooooo eeeeqqqq """"AAAABBBBCCCCDDDD"""" $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""cccc4444"""",,,,66665555,,,,66666666,,,,66667777,,,,66668888))));;;; #### ssssaaaammmmeeee tttthhhhiiiinnnngggg $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""ccccccccxxxxxxxxcccccccc"""",,,,66665555,,,,66666666,,,,66667777,,,,66668888))));;;; #### ffffoooooooo eeeeqqqq """"AAAABBBB\\\\0000\\\\0000CCCCDDDD"""" $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""ssss2222"""",,,,1111,,,,2222))));;;; #### """"\\\\1111\\\\0000\\\\2222\\\\0000"""" oooonnnn lllliiiittttttttlllleeee----eeeennnnddddiiiiaaaannnn #### """"\\\\0000\\\\1111\\\\0000\\\\2222"""" oooonnnn bbbbiiiigggg----eeeennnnddddiiiiaaaannnn $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""aaaa4444"""",,,,""""aaaabbbbccccdddd"""",,,,""""xxxx"""",,,,""""yyyy"""",,,,""""zzzz""""))));;;; #### """"aaaabbbbccccdddd"""" $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""aaaaaaaaaaaaaaaa"""",,,,""""aaaabbbbccccdddd"""",,,,""""xxxx"""",,,,""""yyyy"""",,,,""""zzzz""""))));;;; #### """"aaaaxxxxyyyyzzzz"""" $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""aaaa11114444"""",,,,""""aaaabbbbccccddddeeeeffffgggg""""))));;;; #### """"aaaabbbbccccddddeeeeffffgggg\\\\0000\\\\0000\\\\0000\\\\0000\\\\0000\\\\0000\\\\0000"""" $$$$ffffoooooooo ==== ppppaaaacccckkkk((((""""iiii9999ppppllll"""",,,, ggggmmmmttttiiiimmmmeeee))));;;; #### aaaa rrrreeeeaaaallll ssssttttrrrruuuucccctttt ttttmmmm ((((oooonnnn mmmmyyyy ssssyyyysssstttteeeemmmm aaaannnnyyyywwwwaaaayyyy)))) ssssuuuubbbb bbbbiiiinnnnttttooooddddeeeecccc {{{{ uuuunnnnppppaaaacccckkkk((((""""NNNN"""",,,, ppppaaaacccckkkk((((""""BBBB33332222"""",,,, ssssuuuubbbbssssttttrrrr((((""""0000"""" xxxx 33332222 .... sssshhhhiiiifffftttt,,,, ----33332222))))))))))));;;; }}}} The same template may generally also be used in the unpack function. package NAMESPACE Declares the compilation unit as being in the given namespace. The scope of the package declaration is from the declaration itself through the end of the enclosing block (the same scope as the _l_o_c_a_l_(_) operator). All further unqualified dynamic identifiers will be in this namespace. A package statement only affects dynamic variables--including those you've used _l_o_c_a_l_(_) 16/Feb/96 perl 5.002 with 39 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) on--but _n_o_t lexical variables created with _m_y_(_). Typically it would be the first declaration in a file to be included by the rrrreeeeqqqquuuuiiiirrrreeee or uuuusssseeee operator. You can switch into a package in more than one place; it merely influences which symbol table is used by the compiler for the rest of that block. You can refer to variables and filehandles in other packages by prefixing the identifier with the package name and a double colon: $$$$PPPPaaaacccckkkkaaaaggggeeee::::::::VVVVaaaarrrriiiiaaaabbbblllleeee. If the package name is null, the mmmmaaaaiiiinnnn package as assumed. That is, $$$$::::::::ssssaaaaiiiillll is equivalent to $$$$mmmmaaaaiiiinnnn::::::::ssssaaaaiiiillll. See the section on _P_a_c_k_a_g_e_s in the _p_e_r_l_m_o_d manpage for more information about packages, modules, and classes. See the _p_e_r_l_s_u_b manpage for other scoping issues. pipe READHANDLE,WRITEHANDLE Opens a pair of connected pipes like the corresponding system call. Note that if you set up a loop of piped processes, deadlock can occur unless you are very careful. In addition, note that Perl's pipes use stdio buffering, so you may need to set $| to flush your WRITEHANDLE after each command, depending on the application. See the _o_p_e_n_2 manpage, the _o_p_e_n_3 manpage, and the section on _B_i_d_i_r_e_c_t_i_o_n_a_l _C_o_m_m_u_n_i_c_a_t_i_o_n in the _p_e_r_l_i_p_c manpage for examples of such things. pop ARRAY Pops and returns the last value of the array, shortening the array by 1. Has a similar effect to $$$$ttttmmmmpppp ==== $$$$AAAARRRRRRRRAAAAYYYY[[[[$$$$####AAAARRRRRRRRAAAAYYYY--------]]]];;;; If there are no elements in the array, returns the undefined value. If ARRAY is omitted, pops the @@@@AAAARRRRGGGGVVVV array in the main program, and the @@@@____ array in subroutines, just like _s_h_i_f_t_(_). pos SCALAR Returns the offset of where the last mmmm////////gggg search left off for the variable in question. May be modified to change that offset. print FILEHANDLE LIST print LIST print Prints a string or a comma-separated list of strings. Returns TRUE if successful. FILEHANDLE 16/Feb/96 perl 5.002 with 40 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) may be a scalar variable name, in which case the variable contains the name of or a reference to the filehandle, thus introducing one level of indirection. (NOTE: If FILEHANDLE is a variable and the next token is a term, it may be misinterpreted as an operator unless you interpose a + or put parens around the arguments.) If FILEHANDLE is omitted, prints by default to standard output (or to the last selected output channel--see _s_e_l_e_c_t_(_)). If LIST is also omitted, prints $$$$____ to STDOUT. To set the default output channel to something other than STDOUT use the select operation. Note that, because print takes a LIST, anything in the LIST is evaluated in a list context, and any subroutine that you call will have one or more of its expressions evaluated in a list context. Also be careful not to follow the print keyword with a left parenthesis unless you want the corresponding right parenthesis to terminate the arguments to the print--interpose a + or put parens around all the arguments. Note that if you're storing FILEHANDLES in an array or other expression, you will have to use a block returning its value instead pppprrrriiiinnnntttt {{{{ $$$$ffffiiiilllleeeessss[[[[$$$$iiii]]]] }}}} """"ssssttttuuuuffffffff\\\\nnnn"""";;;; pppprrrriiiinnnntttt {{{{ $$$$OOOOKKKK ???? SSSSTTTTDDDDOOOOUUUUTTTT :::: SSSSTTTTDDDDEEEERRRRRRRR }}}} """"ssssttttuuuuffffffff\\\\nnnn"""";;;; printf FILEHANDLE LIST printf LIST Equivalent to a "print FILEHANDLE _s_p_r_i_n_t_f(LIST)". The first argument of the list will be interpreted as the printf format. push ARRAY,LIST Treats ARRAY as a stack, and pushes the values of LIST onto the end of ARRAY. The length of ARRAY increases by the length of LIST. Has the same effect as ffffoooorrrr $$$$vvvvaaaalllluuuueeee ((((LLLLIIIISSSSTTTT)))) {{{{ $$$$AAAARRRRRRRRAAAAYYYY[[[[++++++++$$$$####AAAARRRRRRRRAAAAYYYY]]]] ==== $$$$vvvvaaaalllluuuueeee;;;; }}}} but is more efficient. Returns the new number of elements in the array. q/STRING/ qq/STRING/ 16/Feb/96 perl 5.002 with 41 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) qx/STRING/ qw/STRING/ Generalized quotes. See the _p_e_r_l_o_p manpage. quotemeta EXPR Returns the value of EXPR with with all regular expression metacharacters backslashed. This is the internal function implementing the \Q escape in double-quoted strings. rand EXPR rand Returns a random fractional number between 0 and the value of EXPR. (EXPR should be positive.) If EXPR is omitted, returns a value between 0 and 1. This function produces repeatable sequences unless _s_r_a_n_d_(_) is invoked. See also _s_r_a_n_d_(_). (Note: if your rand function consistently returns numbers that are too large or too small, then your version of Perl was probably compiled with the wrong number of RANDBITS. As a workaround, you can usually multiply EXPR by the correct power of 2 to get the range you want. This will make your script unportable, however. It's better to recompile if you can.) read FILEHANDLE,SCALAR,LENGTH,OFFSET read FILEHANDLE,SCALAR,LENGTH Attempts to read LENGTH bytes of data into variable SCALAR from the specified FILEHANDLE. Returns the number of bytes actually read, or undef if there was an error. SCALAR will be grown or shrunk to the length actually read. An OFFSET may be specified to place the read data at some other place than the beginning of the string. This call is actually implemented in terms of stdio's fread call. To get a true read system call, see _s_y_s_r_e_a_d_(_). readdir DIRHANDLE Returns the next directory entry for a directory opened by _o_p_e_n_d_i_r_(_). If used in a list context, returns all the rest of the entries in the directory. If there are no more entries, returns an undefined value in a scalar context or a null list in a list context. If you're planning to filetest the return values out of a _r_e_a_d_d_i_r_(_), you'd better prepend the directory in question. Otherwise, since we didn't _c_h_d_i_r_(_) there, it would have been testing the 16/Feb/96 perl 5.002 with 42 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) wrong file. ooooppppeeeennnnddddiiiirrrr((((DDDDIIIIRRRR,,,, $$$$ssssoooommmmeeee____ddddiiiirrrr)))) |||||||| ddddiiiieeee """"ccccaaaannnn''''tttt ooooppppeeeennnnddddiiiirrrr $$$$ssssoooommmmeeee____ddddiiiirrrr:::: $$$$!!!!"""";;;; @@@@ddddoooottttssss ==== ggggrrrreeeepppp {{{{ ////^^^^\\\\....//// &&&&&&&& ----ffff """"$$$$ssssoooommmmeeee____ddddiiiirrrr////$$$$____"""" }}}} rrrreeeeaaaaddddddddiiiirrrr((((DDDDIIIIRRRR))));;;; cccclllloooosssseeeeddddiiiirrrr DDDDIIIIRRRR;;;; readlink EXPR Returns the value of a symbolic link, if symbolic links are implemented. If not, gives a fatal error. If there is some system error, returns the undefined value and sets $! (errno). If EXPR is omitted, uses $$$$____. recv SOCKET,SCALAR,LEN,FLAGS Receives a message on a socket. Attempts to receive LENGTH bytes of data into variable SCALAR from the specified SOCKET filehandle. Actually does a C _r_e_c_v_f_r_o_m_(_), so that it can returns the address of the sender. Returns the undefined value if there's an error. SCALAR will be grown or shrunk to the length actually read. Takes the same flags as the system call of the same name. See the section on _U_D_P_: _M_e_s_s_a_g_e _P_a_s_s_i_n_g in the _p_e_r_l_i_p_c manpage for examples. redo LABEL redo The rrrreeeeddddoooo command restarts the loop block without evaluating the conditional again. The ccccoooonnnnttttiiiinnnnuuuueeee block, if any, is not executed. If the LABEL is omitted, the command refers to the innermost enclosing loop. This command is normally used by programs that want to lie to themselves about what was just input: #### aaaa ssssiiiimmmmpppplllleeeemmmmiiiinnnnddddeeeedddd PPPPaaaassssccccaaaallll ccccoooommmmmmmmeeeennnntttt ssssttttrrrriiiippppppppeeeerrrr #### ((((wwwwaaaarrrrnnnniiiinnnngggg:::: aaaassssssssuuuummmmeeeessss nnnnoooo {{{{ oooorrrr }}}} iiiinnnn ssssttttrrrriiiinnnnggggssss)))) LLLLIIIINNNNEEEE:::: wwwwhhhhiiiilllleeee ((((<<<<SSSSTTTTDDDDIIIINNNN>>>>)))) {{{{ wwwwhhhhiiiilllleeee ((((ssss||||(((({{{{....****}}}}....****)))){{{{....****}}}}||||$$$$1111 ||||)))) {{{{}}}} ssss||||{{{{....****}}}}|||| ||||;;;; iiiiffff ((((ssss||||{{{{....****|||| ||||)))) {{{{ $$$$ffffrrrroooonnnntttt ==== $$$$____;;;; wwwwhhhhiiiilllleeee ((((<<<<SSSSTTTTDDDDIIIINNNN>>>>)))) {{{{ iiiiffff ((((////}}}}////)))) {{{{ #### eeeennnndddd ooooffff ccccoooommmmmmmmeeeennnntttt???? ssss||||^^^^||||$$$$ffffrrrroooonnnntttt{{{{||||;;;; rrrreeeeddddoooo LLLLIIIINNNNEEEE;;;; }}}} }}}} }}}} pppprrrriiiinnnntttt;;;; }}}} 16/Feb/96 perl 5.002 with 43 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ref EXPR Returns a TRUE value if EXPR is a reference, FALSE otherwise. The value returned depends on the type of thing the reference is a reference to. Builtin types include: RRRREEEEFFFF SSSSCCCCAAAALLLLAAAARRRR AAAARRRRRRRRAAAAYYYY HHHHAAAASSSSHHHH CCCCOOOODDDDEEEE GGGGLLLLOOOOBBBB If the referenced object has been blessed into a package, then that package name is returned instead. You can think of _r_e_f_(_) as a _t_y_p_e_o_f_(_) operator. iiiiffff ((((rrrreeeeffff(((($$$$rrrr)))) eeeeqqqq """"HHHHAAAASSSSHHHH"""")))) {{{{ pppprrrriiiinnnntttt """"rrrr iiiissss aaaa rrrreeeeffffeeeerrrreeeennnncccceeee ttttoooo aaaannnn aaaassssssssoooocccciiiiaaaattttiiiivvvveeee aaaarrrrrrrraaaayyyy....\\\\nnnn"""";;;; }}}} iiiiffff ((((!!!!rrrreeeeffff (((($$$$rrrr)))) {{{{ pppprrrriiiinnnntttt """"rrrr iiiissss nnnnooootttt aaaa rrrreeeeffffeeeerrrreeeennnncccceeee aaaatttt aaaallllllll....\\\\nnnn"""";;;; }}}} See also the _p_e_r_l_r_e_f manpage. rename OLDNAME,NEWNAME Changes the name of a file. Returns 1 for success, 0 otherwise. Will not work across filesystem boundaries. require EXPR require Demands some semantics specified by EXPR, or by $$$$____ if EXPR is not supplied. If EXPR is numeric, demands that the current version of Perl ($] or $$$$PPPPEEEERRRRLLLL____VVVVEEEERRRRSSSSIIIIOOOONNNN) be equal or greater than EXPR. Otherwise, demands that a library file be included if it hasn't already been included. The file is included via the do-FILE mechanism, which is essentially just a variety of _e_v_a_l_(_). Has semantics similar to the following subroutine: 16/Feb/96 perl 5.002 with 44 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ssssuuuubbbb rrrreeeeqqqquuuuiiiirrrreeee {{{{ llllooooccccaaaallll(((($$$$ffffiiiilllleeeennnnaaaammmmeeee)))) ==== @@@@____;;;; rrrreeeettttuuuurrrrnnnn 1111 iiiiffff $$$$IIIINNNNCCCC{{{{$$$$ffffiiiilllleeeennnnaaaammmmeeee}}}};;;; llllooooccccaaaallll(((($$$$rrrreeeeaaaallllffffiiiilllleeeennnnaaaammmmeeee,,,,$$$$rrrreeeessssuuuulllltttt))));;;; IIIITTTTEEEERRRR:::: {{{{ ffffoooorrrreeeeaaaacccchhhh $$$$pppprrrreeeeffffiiiixxxx ((((@@@@IIIINNNNCCCC)))) {{{{ $$$$rrrreeeeaaaallllffffiiiilllleeeennnnaaaammmmeeee ==== """"$$$$pppprrrreeeeffffiiiixxxx////$$$$ffffiiiilllleeeennnnaaaammmmeeee"""";;;; iiiiffff ((((----ffff $$$$rrrreeeeaaaallllffffiiiilllleeeennnnaaaammmmeeee)))) {{{{ $$$$rrrreeeessssuuuulllltttt ==== ddddoooo $$$$rrrreeeeaaaallllffffiiiilllleeeennnnaaaammmmeeee;;;; llllaaaasssstttt IIIITTTTEEEERRRR;;;; }}}} }}}} ddddiiiieeee """"CCCCaaaannnn''''tttt ffffiiiinnnndddd $$$$ffffiiiilllleeeennnnaaaammmmeeee iiiinnnn \\\\@@@@IIIINNNNCCCC"""";;;; }}}} ddddiiiieeee $$$$@@@@ iiiiffff $$$$@@@@;;;; ddddiiiieeee """"$$$$ffffiiiilllleeeennnnaaaammmmeeee ddddiiiidddd nnnnooootttt rrrreeeettttuuuurrrrnnnn ttttrrrruuuueeee vvvvaaaalllluuuueeee"""" uuuunnnnlllleeeessssssss $$$$rrrreeeessssuuuulllltttt;;;; $$$$IIIINNNNCCCC{{{{$$$$ffffiiiilllleeeennnnaaaammmmeeee}}}} ==== $$$$rrrreeeeaaaallllffffiiiilllleeeennnnaaaammmmeeee;;;; $$$$rrrreeeessssuuuulllltttt;;;; }}}} Note that the file will not be included twice under the same specified name. The file must return TRUE as the last statement to indicate successful execution of any initialization code, so it's customary to end such a file with "1;" unless you're sure it'll return TRUE otherwise. But it's better just to put the "1111;;;;", in case you add more statements. If EXPR is a bare word, the require assumes a "_._p_m" extension for you, to make it easy to load standard modules. This form of loading of modules does not risk altering your namespace. For a yet-more-powerful import facility, see the the uuuusssseeee(((()))) entry elsewhere in this documentthe _p_e_r_l_m_o_d manpage. reset EXPR reset Generally used in a ccccoooonnnnttttiiiinnnnuuuueeee block at the end of a loop to clear variables and reset ?? searches so that they work again. The expression is interpreted as a list of single characters (hyphens allowed for ranges). All variables and arrays beginning with one of those letters are reset to their pristine state. If the expression is omitted, one-match searches (?pattern?) are reset to match again. Only resets variables or searches in the current package. Always returns 1. Examples: 16/Feb/96 perl 5.002 with 45 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) rrrreeeesssseeeetttt ''''XXXX'''';;;; #### rrrreeeesssseeeetttt aaaallllllll XXXX vvvvaaaarrrriiiiaaaabbbblllleeeessss rrrreeeesssseeeetttt ''''aaaa----zzzz'''';;;; #### rrrreeeesssseeeetttt lllloooowwwweeeerrrr ccccaaaasssseeee vvvvaaaarrrriiiiaaaabbbblllleeeessss rrrreeeesssseeeetttt;;;; #### jjjjuuuusssstttt rrrreeeesssseeeetttt ???????? sssseeeeaaaarrrrcccchhhheeeessss Resetting "A-Z" is not recommended since you'll wipe out your ARGV and ENV arrays. Only resets package variables--lexical variables are unaffected, but they clean themselves up on scope exit anyway, so anymore you probably want to use them instead. See the mmmmyyyy entry elsewhere in this document. return LIST Returns from a subroutine or eval with the value specified. (Note that in the absence of a return a subroutine or _e_v_a_l_(_) will automatically return the value of the last expression evaluated.) reverse LIST In a list context, returns a list value consisting of the elements of LIST in the opposite order. In a scalar context, returns a string value consisting of the bytes of the first element of LIST in the opposite order. pppprrrriiiinnnntttt rrrreeeevvvveeeerrrrsssseeee <<<<>>>>;;;; #### lllliiiinnnneeee ttttaaaacccc uuuunnnnddddeeeeffff $$$$////;;;; pppprrrriiiinnnntttt ssssccccaaaallllaaaarrrr rrrreeeevvvveeeerrrrsssseeee ssssccccaaaallllaaaarrrr <<<<>>>>;;;; #### bbbbyyyytttteeee ttttaaaacccc rewinddir DIRHANDLE Sets the current position to the beginning of the directory for the _r_e_a_d_d_i_r_(_) routine on DIRHANDLE. rindex STR,SUBSTR,POSITION rindex STR,SUBSTR Works just like index except that it returns the position of the LAST occurrence of SUBSTR in STR. If POSITION is specified, returns the last occurrence at or before that position. rmdir FILENAME Deletes the directory specified by FILENAME if it is empty. If it succeeds it returns 1, otherwise it returns 0 and sets $! (errno). If FILENAME is omitted, uses $$$$____. s/// The substitution operator. See the _p_e_r_l_o_p manpage. scalar EXPR Forces EXPR to be interpreted in a scalar context 16/Feb/96 perl 5.002 with 46 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) and returns the value of EXPR. @@@@ccccoooouuuunnnnttttssss ==== (((( ssssccccaaaallllaaaarrrr @@@@aaaa,,,, ssssccccaaaallllaaaarrrr @@@@bbbb,,,, ssssccccaaaallllaaaarrrr @@@@cccc ))));;;; There is no equivalent operator to force an expression to be interpolated in a list context because it's in practice never needed. If you really wanted to do so, however, you could use the construction @@@@{{{{[[[[ ((((ssssoooommmmeeee eeeexxxxpppprrrreeeessssssssiiiioooonnnn)))) ]]]]}}}}, but usually a simple ((((ssssoooommmmeeee eeeexxxxpppprrrreeeessssssssiiiioooonnnn)))) suffices. seek FILEHANDLE,POSITION,WHENCE Randomly positions the file pointer for FILEHANDLE, just like the _f_s_e_e_k_(_) call of stdio. FILEHANDLE may be an expression whose value gives the name of the filehandle. The values for WHENCE are 0 to set the file pointer to POSITION, 1 to set the it to current plus POSITION, and 2 to set it to EOF plus offset. You may use the values SEEK_SET, SEEK_CUR, and SEEK_END for this from POSIX module. Returns 1 upon success, 0 otherwise. On some systems you have to do a seek whenever you switch between reading and writing. Amongst other things, this may have the effect of calling stdio's _c_l_e_a_r_e_r_r(3). A "whence" of 1 (SEEK_CUR) is useful for not moving the file pointer: sssseeeeeeeekkkk((((TTTTEEEESSSSTTTT,,,,0000,,,,1111))));;;; This is also useful for applications emulating ttttaaaaiiiillll ----ffff. Once you hit EOF on your read, and then sleep for a while, you might have to stick in a _s_e_e_k_(_) to reset things. First the simple trick listed above to clear the filepointer. The _s_e_e_k_(_) doesn't change the current position, but it _d_o_e_s clear the end-of-file condition on the handle, so that the next C<<FILE<>> makes Perl try again to read something. Hopefully. If that doesn't work (some stdios are particularly cantankerous), then you may need something more like this: ffffoooorrrr ((((;;;;;;;;)))) {{{{ ffffoooorrrr (((($$$$ccccuuuurrrrppppoooossss ==== tttteeeellllllll((((FFFFIIIILLLLEEEE))));;;; $$$$____ ==== <<<<FFFFIIIILLLLEEEE>>>>;;;; $$$$ccccuuuurrrrppppoooossss ==== tttteeeellllllll((((FFFFIIIILLLLEEEE)))))))) {{{{ #### sssseeeeaaaarrrrcccchhhh ffffoooorrrr ssssoooommmmeeee ssssttttuuuuffffffff aaaannnndddd ppppuuuutttt iiiitttt iiiinnnnttttoooo ffffiiiilllleeeessss }}}} sssslllleeeeeeeepppp(((($$$$ffffoooorrrr____aaaa____wwwwhhhhiiiilllleeee))));;;; sssseeeeeeeekkkk((((FFFFIIIILLLLEEEE,,,, $$$$ccccuuuurrrrppppoooossss,,,, 0000))));;;; }}}} 16/Feb/96 perl 5.002 with 47 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) seekdir DIRHANDLE,POS Sets the current position for the _r_e_a_d_d_i_r_(_) routine on DIRHANDLE. POS must be a value returned by _t_e_l_l_d_i_r_(_). Has the same caveats about possible directory compaction as the corresponding system library routine. select FILEHANDLE select Returns the currently selected filehandle. Sets the current default filehandle for output, if FILEHANDLE is supplied. This has two effects: first, a wwwwrrrriiiitttteeee or a pppprrrriiiinnnntttt without a filehandle will default to this FILEHANDLE. Second, references to variables related to output will refer to this output channel. For example, if you have to set the top of form format for more than one output channel, you might do the following: sssseeeelllleeeecccctttt((((RRRREEEEPPPPOOOORRRRTTTT1111))));;;; $$$$^^^^ ==== ''''rrrreeeeppppoooorrrrtttt1111____ttttoooopppp'''';;;; sssseeeelllleeeecccctttt((((RRRREEEEPPPPOOOORRRRTTTT2222))));;;; $$$$^^^^ ==== ''''rrrreeeeppppoooorrrrtttt2222____ttttoooopppp'''';;;; FILEHANDLE may be an expression whose value gives the name of the actual filehandle. Thus: $$$$oooollllddddffffhhhh ==== sssseeeelllleeeecccctttt((((SSSSTTTTDDDDEEEERRRRRRRR))));;;; $$$$|||| ==== 1111;;;; sssseeeelllleeeecccctttt(((($$$$oooollllddddffffhhhh))));;;; Some programmers may prefer to think of filehandles as objects with methods, preferring to write the last example as: uuuusssseeee FFFFiiiilllleeeeHHHHaaaannnnddddlllleeee;;;; SSSSTTTTDDDDEEEERRRRRRRR---->>>>aaaauuuuttttoooofffflllluuuusssshhhh((((1111))));;;; select RBITS,WBITS,EBITS,TIMEOUT This calls the _s_e_l_e_c_t(2) system call with the bitmasks specified, which can be constructed using _f_i_l_e_n_o_(_) and _v_e_c_(_), along these lines: $$$$rrrriiiinnnn ==== $$$$wwwwiiiinnnn ==== $$$$eeeeiiiinnnn ==== '''''''';;;; vvvveeeecccc(((($$$$rrrriiiinnnn,,,,ffffiiiilllleeeennnnoooo((((SSSSTTTTDDDDIIIINNNN)))),,,,1111)))) ==== 1111;;;; vvvveeeecccc(((($$$$wwwwiiiinnnn,,,,ffffiiiilllleeeennnnoooo((((SSSSTTTTDDDDOOOOUUUUTTTT)))),,,,1111)))) ==== 1111;;;; $$$$eeeeiiiinnnn ==== $$$$rrrriiiinnnn |||| $$$$wwwwiiiinnnn;;;; If you want to select on many filehandles you might wish to write a subroutine: 16/Feb/96 perl 5.002 with 48 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ssssuuuubbbb ffffhhhhbbbbiiiittttssss {{{{ llllooooccccaaaallll((((@@@@ffffhhhhlllliiiisssstttt)))) ==== sssspppplllliiiitttt(((('''' '''',,,,$$$$____[[[[0000]]]]))));;;; llllooooccccaaaallll(((($$$$bbbbiiiittttssss))));;;; ffffoooorrrr ((((@@@@ffffhhhhlllliiiisssstttt)))) {{{{ vvvveeeecccc(((($$$$bbbbiiiittttssss,,,,ffffiiiilllleeeennnnoooo(((($$$$____)))),,,,1111)))) ==== 1111;;;; }}}} $$$$bbbbiiiittttssss;;;; }}}} $$$$rrrriiiinnnn ==== ffffhhhhbbbbiiiittttssss((((''''SSSSTTTTDDDDIIIINNNN TTTTTTTTYYYY SSSSOOOOCCCCKKKK''''))));;;; The usual idiom is: (((($$$$nnnnffffoooouuuunnnndddd,,,,$$$$ttttiiiimmmmeeeelllleeeefffftttt)))) ==== sssseeeelllleeeecccctttt(((($$$$rrrroooouuuutttt====$$$$rrrriiiinnnn,,,, $$$$wwwwoooouuuutttt====$$$$wwwwiiiinnnn,,,, $$$$eeeeoooouuuutttt====$$$$eeeeiiiinnnn,,,, $$$$ttttiiiimmmmeeeeoooouuuutttt))));;;; or to block until something becomes ready just do this $$$$nnnnffffoooouuuunnnndddd ==== sssseeeelllleeeecccctttt(((($$$$rrrroooouuuutttt====$$$$rrrriiiinnnn,,,, $$$$wwwwoooouuuutttt====$$$$wwwwiiiinnnn,,,, $$$$eeeeoooouuuutttt====$$$$eeeeiiiinnnn,,,, uuuunnnnddddeeeeffff))));;;; Most systems do not both to return anything useful in $$$$ttttiiiimmmmeeeelllleeeefffftttt, so calling _s_e_l_e_c_t_(_) in a scalar context just returns $$$$nnnnffffoooouuuunnnndddd. Any of the bitmasks can also be undef. The timeout, if specified, is in seconds, which may be fractional. Note: not all implementations are capable of returning the $$$$ttttiiiimmmmeeeelllleeeefffftttt. If not, they always return $$$$ttttiiiimmmmeeeelllleeeefffftttt equal to the supplied $$$$ttttiiiimmmmeeeeoooouuuutttt. You can effect a 250-microsecond sleep this way: sssseeeelllleeeecccctttt((((uuuunnnnddddeeeeffff,,,, uuuunnnnddddeeeeffff,,,, uuuunnnnddddeeeeffff,,,, 0000....22225555))));;;; WWWWAAAARRRRNNNNIIIINNNNGGGG: Do not attempt to mix buffered I/O (like _r_e_a_d_(_) or <FH>) with _s_e_l_e_c_t_(_). You have to use _s_y_s_r_e_a_d_(_) instead. semctl ID,SEMNUM,CMD,ARG Calls the System V IPC function semctl. If CMD is &IPC_STAT or &GETALL, then ARG must be a variable which will hold the returned semid_ds structure or semaphore value array. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise. semget KEY,NSEMS,FLAGS Calls the System V IPC function semget. Returns the semaphore id, or the undefined value if there is an error. semop KEY,OPSTRING Calls the System V IPC function semop to perform 16/Feb/96 perl 5.002 with 49 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) semaphore operations such as signaling and waiting. OPSTRING must be a packed array of semop structures. Each semop structure can be generated with ppppaaaacccckkkk((((""""ssssssssssss"""",,,, $$$$sssseeeemmmmnnnnuuuummmm,,,, $$$$sssseeeemmmmoooopppp,,,, $$$$sssseeeemmmmffffllllaaaagggg)))). The number of semaphore operations is implied by the length of OPSTRING. Returns TRUE if successful, or FALSE if there is an error. As an example, the following code waits on semaphore $$$$sssseeeemmmmnnnnuuuummmm of semaphore id $$$$sssseeeemmmmiiiidddd:::: $$$$sssseeeemmmmoooopppp ==== ppppaaaacccckkkk((((""""ssssssssssss"""",,,, $$$$sssseeeemmmmnnnnuuuummmm,,,, ----1111,,,, 0000))));;;; ddddiiiieeee """"SSSSeeeemmmmaaaapppphhhhoooorrrreeee ttttrrrroooouuuubbbblllleeee:::: $$$$!!!!\\\\nnnn"""" uuuunnnnlllleeeessssssss sssseeeemmmmoooopppp(((($$$$sssseeeemmmmiiiidddd,,,, $$$$sssseeeemmmmoooopppp))));;;; To signal the semaphore, replace "-1" with "1". send SOCKET,MSG,FLAGS,TO send SOCKET,MSG,FLAGS Sends a message on a socket. Takes the same flags as the system call of the same name. On unconnected sockets you must specify a destination to send TO, in which case it does a C _s_e_n_d_t_o_(_). Returns the number of characters sent, or the undefined value if there is an error. See the section on _U_D_P_: _M_e_s_s_a_g_e _P_a_s_s_i_n_g in the _p_e_r_l_i_p_c manpage for examples. setpgrp PID,PGRP Sets the current process group for the specified PID, 0 for the current process. Will produce a fatal error if used on a machine that doesn't implement _s_e_t_p_g_r_p(2). setpriority WHICH,WHO,PRIORITY Sets the current priority for a process, a process group, or a user. (See _s_e_t_p_r_i_o_r_i_t_y(2).) Will produce a fatal error if used on a machine that doesn't implement _s_e_t_p_r_i_o_r_i_t_y(2). setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL Sets the socket option requested. Returns undefined if there is an error. OPTVAL may be specified as undef if you don't want to pass an argument. shift ARRAY shift Shifts the first value of the array off and returns it, shortening the array by 1 and moving everything down. If there are no elements in the array, returns the undefined value. If ARRAY is omitted, shifts the @@@@AAAARRRRGGGGVVVV array in the main program, and the @@@@____ array in subroutines. (This is determined lexically.) See also _u_n_s_h_i_f_t_(_), 16/Feb/96 perl 5.002 with 50 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) _p_u_s_h_(_), and _p_o_p_(_). _S_h_i_f_t_(_) and _u_n_s_h_i_f_t_(_) do the same thing to the left end of an array that _p_u_s_h_(_) and _p_o_p_(_) do to the right end. shmctl ID,CMD,ARG Calls the System V IPC function shmctl. If CMD is &IPC_STAT, then ARG must be a variable which will hold the returned shmid_ds structure. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise. shmget KEY,SIZE,FLAGS Calls the System V IPC function shmget. Returns the shared memory segment id, or the undefined value if there is an error. shmread ID,VAR,POS,SIZE shmwrite ID,STRING,POS,SIZE Reads or writes the System V shared memory segment ID starting at position POS for size SIZE by attaching to it, copying in/out, and detaching from it. When reading, VAR must be a variable which will hold the data read. When writing, if STRING is too long, only SIZE bytes are used; if STRING is too short, nulls are written to fill out SIZE bytes. Return TRUE if successful, or FALSE if there is an error. shutdown SOCKET,HOW Shuts down a socket connection in the manner indicated by HOW, which has the same interpretation as in the system call of the same name. sin EXPR Returns the sine of EXPR (expressed in radians). If EXPR is omitted, returns sine of $$$$____. sleep EXPR sleep Causes the script to sleep for EXPR seconds, or forever if no EXPR. May be interrupted by sending the process a SIGALRM. Returns the number of seconds actually slept. You probably cannot mix _a_l_a_r_m_(_) and _s_l_e_e_p_(_) calls, since _s_l_e_e_p_(_) is often implemented using _a_l_a_r_m_(_). On some older systems, it may sleep up to a full second less than what you requested, depending on how it counts seconds. Most modern systems always sleep the full amount. 16/Feb/96 perl 5.002 with 51 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) For delays of finer granularity than one second, you may use Perl's _s_y_s_c_a_l_l_(_) interface to access _s_e_t_i_t_i_m_e_r(2) if your system supports it, or else see the sssseeeelllleeeecccctttt(((()))) entry elsewhere in this documentbelow. socket SOCKET,DOMAIN,TYPE,PROTOCOL Opens a socket of the specified kind and attaches it to filehandle SOCKET. DOMAIN, TYPE and PROTOCOL are specified the same as for the system call of the same name. You should "use Socket;" first to get the proper definitions imported. See the example in the section on _S_o_c_k_e_t_s_: _C_l_i_e_n_t_/_S_e_r_v_e_r _C_o_m_m_u_n_i_c_a_t_i_o_n in the _p_e_r_l_i_p_c manpage. socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL Creates an unnamed pair of sockets in the specified domain, of the specified type. DOMAIN, TYPE and PROTOCOL are specified the same as for the system call of the same name. If unimplemented, yields a fatal error. Returns TRUE if successful. sort SUBNAME LIST sort BLOCK LIST sort LIST Sorts the LIST and returns the sorted list value. Nonexistent values of arrays are stripped out. If SUBNAME or BLOCK is omitted, sorts in standard string comparison order. If SUBNAME is specified, it gives the name of a subroutine that returns an integer less than, equal to, or greater than 0, depending on how the elements of the array are to be ordered. (The <=> and cmp operators are extremely useful in such routines.) SUBNAME may be a scalar variable name, in which case the value provides the name of the subroutine to use. In place of a SUBNAME, you can provide a BLOCK as an anonymous, in-line sort subroutine. In the interests of efficiency the normal calling code for subroutines is bypassed, with the following effects: the subroutine may not be a recursive subroutine, and the two elements to be compared are passed into the subroutine not via @@@@____ but as the package global variables $$$$aaaa and $$$$bbbb (see example below). They are passed by reference, so don't modify $$$$aaaa and $$$$bbbb. And don't try to declare them as lexicals either. Examples: 16/Feb/96 perl 5.002 with 52 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) #### ssssoooorrrrtttt lllleeeexxxxiiiiccccaaaallllllllyyyy @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt @@@@ffffiiiilllleeeessss;;;; #### ssssaaaammmmeeee tttthhhhiiiinnnngggg,,,, bbbbuuuutttt wwwwiiiitttthhhh eeeexxxxpppplllliiiicccciiiitttt ssssoooorrrrtttt rrrroooouuuuttttiiiinnnneeee @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$aaaa ccccmmmmpppp $$$$bbbb}}}} @@@@ffffiiiilllleeeessss;;;; #### nnnnoooowwww ccccaaaasssseeee----iiiinnnnsssseeeennnnssssiiiittttiiiivvvveeeellllyyyy @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{ uuuucccc(((($$$$aaaa)))) ccccmmmmpppp uuuucccc(((($$$$bbbb))))}}}} @@@@ffffiiiilllleeeessss;;;; #### ssssaaaammmmeeee tttthhhhiiiinnnngggg iiiinnnn rrrreeeevvvveeeerrrrsssseeeedddd oooorrrrddddeeeerrrr @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$bbbb ccccmmmmpppp $$$$aaaa}}}} @@@@ffffiiiilllleeeessss;;;; #### ssssoooorrrrtttt nnnnuuuummmmeeeerrrriiiiccccaaaallllllllyyyy aaaasssscccceeeennnnddddiiiinnnngggg @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$aaaa <<<<====>>>> $$$$bbbb}}}} @@@@ffffiiiilllleeeessss;;;; #### ssssoooorrrrtttt nnnnuuuummmmeeeerrrriiiiccccaaaallllllllyyyy ddddeeeesssscccceeeennnnddddiiiinnnngggg @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$bbbb <<<<====>>>> $$$$aaaa}}}} @@@@ffffiiiilllleeeessss;;;; #### ssssoooorrrrtttt uuuussssiiiinnnngggg eeeexxxxpppplllliiiicccciiiitttt ssssuuuubbbbrrrroooouuuuttttiiiinnnneeee nnnnaaaammmmeeee ssssuuuubbbb bbbbyyyyaaaaggggeeee {{{{ $$$$aaaaggggeeee{{{{$$$$aaaa}}}} <<<<====>>>> $$$$aaaaggggeeee{{{{$$$$bbbb}}}};;;; #### pppprrrreeeessssuuuummmmiiiinnnngggg iiiinnnntttteeeeggggeeeerrrrssss }}}} @@@@ssssoooorrrrtttteeeeddddccccllllaaaassssssss ==== ssssoooorrrrtttt bbbbyyyyaaaaggggeeee @@@@ccccllllaaaassssssss;;;; #### tttthhhhiiiissss ssssoooorrrrttttssss tttthhhheeee %%%%aaaaggggeeee aaaassssssssoooocccciiiiaaaattttiiiivvvveeee aaaarrrrrrrraaaayyyyssss bbbbyyyy vvvvaaaalllluuuueeee #### iiiinnnnsssstttteeeeaaaadddd ooooffff kkkkeeeeyyyy uuuussssiiiinnnngggg aaaannnn iiiinnnnlllliiiinnnneeee ffffuuuunnnnccccttttiiiioooonnnn @@@@eeeellllddddeeeesssstttt ==== ssssoooorrrrtttt {{{{ $$$$aaaaggggeeee{{{{$$$$bbbb}}}} <<<<====>>>> $$$$aaaaggggeeee{{{{$$$$aaaa}}}} }}}} kkkkeeeeyyyyssss %%%%aaaaggggeeee;;;; ssssuuuubbbb bbbbaaaacccckkkkwwwwaaaarrrrddddssss {{{{ $$$$bbbb ccccmmmmpppp $$$$aaaa;;;; }}}} @@@@hhhhaaaarrrrrrrryyyy ==== ((((''''ddddoooogggg'''',,,,''''ccccaaaatttt'''',,,,''''xxxx'''',,,,''''CCCCaaaaiiiinnnn'''',,,,''''AAAAbbbbeeeellll''''))));;;; @@@@ggggeeeeoooorrrrggggeeee ==== ((((''''ggggoooonnnneeee'''',,,,''''cccchhhhaaaasssseeeedddd'''',,,,''''yyyyzzzz'''',,,,''''PPPPuuuunnnniiiisssshhhheeeedddd'''',,,,''''AAAAxxxxeeeedddd''''))));;;; pppprrrriiiinnnntttt ssssoooorrrrtttt @@@@hhhhaaaarrrrrrrryyyy;;;; #### pppprrrriiiinnnnttttssss AAAAbbbbeeeellllCCCCaaaaiiiinnnnccccaaaattttddddooooggggxxxx pppprrrriiiinnnntttt ssssoooorrrrtttt bbbbaaaacccckkkkwwwwaaaarrrrddddssss @@@@hhhhaaaarrrrrrrryyyy;;;; #### pppprrrriiiinnnnttttssss xxxxddddooooggggccccaaaattttCCCCaaaaiiiinnnnAAAAbbbbeeeellll pppprrrriiiinnnntttt ssssoooorrrrtttt @@@@ggggeeeeoooorrrrggggeeee,,,, ''''ttttoooo'''',,,, @@@@hhhhaaaarrrrrrrryyyy;;;; #### pppprrrriiiinnnnttttssss AAAAbbbbeeeellllAAAAxxxxeeeeddddCCCCaaaaiiiinnnnPPPPuuuunnnniiiisssshhhheeeeddddccccaaaattttcccchhhhaaaasssseeeeddddddddooooggggggggoooonnnneeeettttooooxxxxyyyyzzzz #### iiiinnnneeeeffffffffiiiicccciiiieeeennnnttttllllyyyy ssssoooorrrrtttt bbbbyyyy ddddeeeesssscccceeeennnnddddiiiinnnngggg nnnnuuuummmmeeeerrrriiiicccc ccccoooommmmppppaaaarrrreeee uuuussssiiiinnnngggg #### tttthhhheeee ffffiiiirrrrsssstttt iiiinnnntttteeeeggggeeeerrrr aaaafffftttteeeerrrr tttthhhheeee ffffiiiirrrrsssstttt ==== ssssiiiiggggnnnn,,,, oooorrrr tttthhhheeee #### wwwwhhhhoooolllleeee rrrreeeeccccoooorrrrdddd ccccaaaasssseeee----iiiinnnnsssseeeennnnssssiiiittttiiiivvvveeeellllyyyy ooootttthhhheeeerrrrwwwwiiiisssseeee @@@@nnnneeeewwww ==== ssssoooorrrrtttt {{{{ (((($$$$bbbb ====~~~~ ////====((((\\\\dddd++++))))////))))[[[[0000]]]] <<<<====>>>> (((($$$$aaaa ====~~~~ ////====((((\\\\dddd++++))))////))))[[[[0000]]]] |||||||| uuuucccc(((($$$$aaaa)))) ccccmmmmpppp uuuucccc(((($$$$bbbb)))) }}}} @@@@oooolllldddd;;;; 16/Feb/96 perl 5.002 with 53 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) #### ssssaaaammmmeeee tttthhhhiiiinnnngggg,,,, bbbbuuuutttt mmmmuuuucccchhhh mmmmoooorrrreeee eeeeffffffffiiiicccciiiieeeennnnttttllllyyyy;;;; #### wwwweeee''''llllllll bbbbuuuuiiiilllldddd aaaauuuuxxxxiiiilllliiiiaaaarrrryyyy iiiinnnnddddiiiicccceeeessss iiiinnnnsssstttteeeeaaaadddd #### ffffoooorrrr ssssppppeeeeeeeedddd @@@@nnnnuuuummmmssss ==== @@@@ccccaaaappppssss ==== (((())));;;; ffffoooorrrr ((((@@@@oooolllldddd)))) {{{{ ppppuuuusssshhhh @@@@nnnnuuuummmmssss,,,, ////====((((\\\\dddd++++))))////;;;; ppppuuuusssshhhh @@@@ccccaaaappppssss,,,, uuuucccc(((($$$$____))));;;; }}}} @@@@nnnneeeewwww ==== @@@@oooolllldddd[[[[ ssssoooorrrrtttt {{{{ $$$$nnnnuuuummmmssss[[[[$$$$bbbb]]]] <<<<====>>>> $$$$nnnnuuuummmmssss[[[[$$$$aaaa]]]] |||||||| $$$$ccccaaaappppssss[[[[$$$$aaaa]]]] ccccmmmmpppp $$$$ccccaaaappppssss[[[[$$$$bbbb]]]] }}}} 0000........$$$$####oooolllldddd ]]]];;;; #### ssssaaaammmmeeee tttthhhhiiiinnnngggg uuuussssiiiinnnngggg aaaa SSSScccchhhhwwwwaaaarrrrttttzzzziiiiaaaannnn TTTTrrrraaaannnnssssffffoooorrrrmmmm ((((nnnnoooo tttteeeemmmmppppssss)))) @@@@nnnneeeewwww ==== mmmmaaaapppp {{{{ $$$$____---->>>>[[[[0000]]]] }}}} ssssoooorrrrtttt {{{{ $$$$bbbb---->>>>[[[[1111]]]] <<<<====>>>> $$$$aaaa---->>>>[[[[1111]]]] |||||||| $$$$aaaa---->>>>[[[[2222]]]] ccccmmmmpppp $$$$bbbb---->>>>[[[[2222]]]] }}}} mmmmaaaapppp {{{{ [[[[$$$$____,,,, ////====((((\\\\dddd++++))))////,,,, uuuucccc(((($$$$____))))]]]] }}}} @@@@oooolllldddd;;;; If you're and using strict, you _M_U_S_T _N_O_T declare $$$$aaaa and $$$$bbbb as lexicals. They are package globals. That means if you're in the mmmmaaaaiiiinnnn package, it's @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$mmmmaaaaiiiinnnn::::::::bbbb <<<<====>>>> $$$$mmmmaaaaiiiinnnn::::::::aaaa}}}} @@@@ffffiiiilllleeeessss;;;; or just @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$::::::::bbbb <<<<====>>>> $$$$::::::::aaaa}}}} @@@@ffffiiiilllleeeessss;;;; but if you're in the FFFFooooooooPPPPaaaacccckkkk package, it's @@@@aaaarrrrttttiiiicccclllleeeessss ==== ssssoooorrrrtttt {{{{$$$$FFFFooooooooPPPPaaaacccckkkk::::::::bbbb <<<<====>>>> $$$$FFFFooooooooPPPPaaaacccckkkk::::::::aaaa}}}} @@@@ffffiiiilllleeeessss;;;; splice ARRAY,OFFSET,LENGTH,LIST splice ARRAY,OFFSET,LENGTH splice ARRAY,OFFSET Removes the elements designated by OFFSET and LENGTH from an array, and replaces them with the elements of LIST, if any. Returns the elements removed from the array. The array grows or shrinks as necessary. If LENGTH is omitted, removes everything from OFFSET onward. The following equivalencies hold (assuming $[ == 0): 16/Feb/96 perl 5.002 with 54 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ppppuuuusssshhhh((((@@@@aaaa,,,,$$$$xxxx,,,,$$$$yyyy)))) sssspppplllliiiicccceeee((((@@@@aaaa,,,,$$$$####aaaa++++1111,,,,0000,,,,$$$$xxxx,,,,$$$$yyyy)))) ppppoooopppp((((@@@@aaaa)))) sssspppplllliiiicccceeee((((@@@@aaaa,,,,----1111)))) sssshhhhiiiifffftttt((((@@@@aaaa)))) sssspppplllliiiicccceeee((((@@@@aaaa,,,,0000,,,,1111)))) uuuunnnnsssshhhhiiiifffftttt((((@@@@aaaa,,,,$$$$xxxx,,,,$$$$yyyy)))) sssspppplllliiiicccceeee((((@@@@aaaa,,,,0000,,,,0000,,,,$$$$xxxx,,,,$$$$yyyy)))) $$$$aaaa[[[[$$$$xxxx]]]] ==== $$$$yyyy sssspppplllliiiicccceeee((((@@@@aaaa,,,,$$$$xxxx,,,,1111,,,,$$$$yyyy))));;;; Example, assuming array lengths are passed before arrays: ssssuuuubbbb aaaaeeeeqqqq {{{{ #### ccccoooommmmppppaaaarrrreeee ttttwwwwoooo lllliiiisssstttt vvvvaaaalllluuuueeeessss llllooooccccaaaallll((((@@@@aaaa)))) ==== sssspppplllliiiicccceeee((((@@@@____,,,,0000,,,,sssshhhhiiiifffftttt))));;;; llllooooccccaaaallll((((@@@@bbbb)))) ==== sssspppplllliiiicccceeee((((@@@@____,,,,0000,,,,sssshhhhiiiifffftttt))));;;; rrrreeeettttuuuurrrrnnnn 0000 uuuunnnnlllleeeessssssss @@@@aaaa ======== @@@@bbbb;;;; #### ssssaaaammmmeeee lllleeeennnn???? wwwwhhhhiiiilllleeee ((((@@@@aaaa)))) {{{{ rrrreeeettttuuuurrrrnnnn 0000 iiiiffff ppppoooopppp((((@@@@aaaa)))) nnnneeee ppppoooopppp((((@@@@bbbb))));;;; }}}} rrrreeeettttuuuurrrrnnnn 1111;;;; }}}} iiiiffff ((((&&&&aaaaeeeeqqqq(((($$$$lllleeeennnn,,,,@@@@ffffoooooooo[[[[1111........$$$$lllleeeennnn]]]],,,,0000++++@@@@bbbbaaaarrrr,,,,@@@@bbbbaaaarrrr)))))))) {{{{ ............ }}}} split /PATTERN/,EXPR,LIMIT split /PATTERN/,EXPR split /PATTERN/ split Splits a string into an array of strings, and returns it. If not in a list context, returns the number of fields found and splits into the @@@@____ array. (In a list context, you can force the split into @@@@____ by using ???????? as the pattern delimiters, but it still returns the array value.) The use of implicit split to @@@@____ is deprecated, however. If EXPR is omitted, splits the $$$$____ string. If PATTERN is also omitted, splits on whitespace (after skipping any leading whitespace). Anything matching PATTERN is taken to be a delimiter separating the fields. (Note that the delimiter may be longer than one character.) If LIMIT is specified and is not negative, splits into no more than that many fields (though it may split into fewer). If LIMIT is unspecified, trailing null fields are stripped (which potential users of _p_o_p_(_) would do well to remember). If LIMIT is negative, it is treated as if an arbitrarily large LIMIT had been specified. A pattern matching the null string (not to be confused with a null pattern ////////, which is just one member of the set of patterns matching a null 16/Feb/96 perl 5.002 with 55 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) string) will split the value of EXPR into separate characters at each point it matches that way. For example: pppprrrriiiinnnntttt jjjjooooiiiinnnn((((''''::::'''',,,, sssspppplllliiiitttt((((//// ****////,,,, ''''hhhhiiii tttthhhheeeerrrreeee''''))))))));;;; produces the output 'h:i:t:h:e:r:e'. The LIMIT parameter can be used to partially split a line (((($$$$llllooooggggiiiinnnn,,,, $$$$ppppaaaasssssssswwwwdddd,,,, $$$$rrrreeeemmmmaaaaiiiinnnnddddeeeerrrr)))) ==== sssspppplllliiiitttt((((////::::////,,,, $$$$____,,,, 3333))));;;; When assigning to a list, if LIMIT is omitted, Perl supplies a LIMIT one larger than the number of variables in the list, to avoid unnecessary work. For the list above LIMIT would have been 4 by default. In time critical applications it behooves you not to split into more fields than you really need. If the PATTERN contains parentheses, additional array elements are created from each matching substring in the delimiter. sssspppplllliiiitttt((((////(((([[[[,,,,----]]]]))))////,,,, """"1111----11110000,,,,22220000""""))));;;; produces the list value ((((1111,,,, ''''----'''',,,, 11110000,,,, '''',,,,'''',,,, 22220000)))) If you had the entire header of a normal Unix email message in $$$$hhhheeeeaaaaddddeeeerrrr, you could split it up into fields and their values this way: $$$$hhhheeeeaaaaddddeeeerrrr ====~~~~ ssss////\\\\nnnn\\\\ssss++++//// ////gggg;;;; #### ffffiiiixxxx ccccoooonnnnttttiiiinnnnuuuuaaaattttiiiioooonnnn lllliiiinnnneeeessss %%%%hhhhddddrrrrssss ==== ((((UUUUNNNNIIIIXXXX____FFFFRRRROOOOMMMM ====>>>> sssspppplllliiiitttt ////^^^^((((....****????))))::::\\\\ssss****////mmmm,,,, $$$$hhhheeeeaaaaddddeeeerrrr))));;;; The pattern ////PPPPAAAATTTTTTTTEEEERRRRNNNN//// may be replaced with an expression to specify patterns that vary at runtime. (To do runtime compilation only once, use ////$$$$vvvvaaaarrrriiiiaaaabbbblllleeee////oooo.) As a special case, specifying a PATTERN of space ('''' '''') will split on white space just as split with no arguments does. Thus, split(' ') can be used to emulate aaaawwwwkkkk's default behavior, whereas sssspppplllliiiitttt((((//// ////)))) will give you as many null initial fields as there are leading spaces. A split on /\s+/ is like a split(' ') except that any leading whitespace produces a null first field. A split with no arguments really does a sssspppplllliiiitttt(((('''' '''',,,, $$$$____)))) internally. 16/Feb/96 perl 5.002 with 56 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) Example: ooooppppeeeennnn((((ppppaaaasssssssswwwwdddd,,,, ''''////eeeettttcccc////ppppaaaasssssssswwwwdddd''''))));;;; wwwwhhhhiiiilllleeee ((((<<<<ppppaaaasssssssswwwwdddd>>>>)))) {{{{ (((($$$$llllooooggggiiiinnnn,,,, $$$$ppppaaaasssssssswwwwdddd,,,, $$$$uuuuiiiidddd,,,, $$$$ggggiiiidddd,,,, $$$$ggggccccoooossss,,,, $$$$hhhhoooommmmeeee,,,, $$$$sssshhhheeeellllllll)))) ==== sssspppplllliiiitttt((((////::::////))));;;; ............ }}}} (Note that $$$$sssshhhheeeellllllll above will still have a newline on it. See the cccchhhhoooopppp, cccchhhhoooommmmpppp, and jjjjooooiiiinnnn entries elsewhere in this document.) sprintf FORMAT,LIST Returns a string formatted by the usual printf conventions of the C language. See the _s_p_r_i_n_t_f_(_3_) manpage or the _p_r_i_n_t_f_(_3_) manpage on your system for details. (The * character for an indirectly specified length is not supported, but you can get the same effect by interpolating a variable into the pattern.) Some C libraries' implementations of _s_p_r_i_n_t_f_(_) can dump core when fed ludicrous arguments. sqrt EXPR Return the square root of EXPR. If EXPR is omitted, returns square root of $$$$____. srand EXPR Sets the random number seed for the rrrraaaannnndddd operator. If EXPR is omitted, does ssssrrrraaaannnndddd((((ttttiiiimmmmeeee)))). Many folks use an explicit ssssrrrraaaannnndddd((((ttttiiiimmmmeeee ^^^^ $$$$$$$$)))) instead. Of course, you'd need something much more random than that for cryptographic purposes, since it's easy to guess the current time. Checksumming the compressed output of rapidly changing operating system status programs is the usual method. Examples are posted regularly to the comp.security.unix newsgroup. stat FILEHANDLE stat EXPR Returns a 13-element array giving the status info for a file, either the file opened via FILEHANDLE, or named by EXPR. Returns a null list if the stat fails. Typically used as follows: (((($$$$ddddeeeevvvv,,,,$$$$iiiinnnnoooo,,,,$$$$mmmmooooddddeeee,,,,$$$$nnnnlllliiiinnnnkkkk,,,,$$$$uuuuiiiidddd,,,,$$$$ggggiiiidddd,,,,$$$$rrrrddddeeeevvvv,,,,$$$$ssssiiiizzzzeeee,,,, $$$$aaaattttiiiimmmmeeee,,,,$$$$mmmmttttiiiimmmmeeee,,,,$$$$ccccttttiiiimmmmeeee,,,,$$$$bbbbllllkkkkssssiiiizzzzeeee,,,,$$$$bbbblllloooocccckkkkssss)))) ==== ssssttttaaaatttt(((($$$$ffffiiiilllleeeennnnaaaammmmeeee))));;;; Not all fields are supported on all filesystem types. Here are the meaning of the fields: 16/Feb/96 perl 5.002 with 57 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) ddddeeeevvvv ddddeeeevvvviiiicccceeee nnnnuuuummmmbbbbeeeerrrr ooooffff ffffiiiilllleeeessssyyyysssstttteeeemmmm iiiinnnnoooo iiiinnnnooooddddeeee nnnnuuuummmmbbbbeeeerrrr mmmmooooddddeeee ffffiiiilllleeee mmmmooooddddeeee ((((ttttyyyyppppeeee aaaannnndddd ppppeeeerrrrmmmmiiiissssssssiiiioooonnnnssss)))) nnnnlllliiiinnnnkkkk nnnnuuuummmmbbbbeeeerrrr ooooffff ((((hhhhaaaarrrrdddd)))) lllliiiinnnnkkkkssss ttttoooo tttthhhheeee ffffiiiilllleeee uuuuiiiidddd nnnnuuuummmmeeeerrrriiiicccc uuuusssseeeerrrr IIIIDDDD ooooffff ffffiiiilllleeee''''ssss oooowwwwnnnneeeerrrr ggggiiiidddd nnnnuuuummmmeeeerrrr ggggrrrroooouuuupppp IIIIDDDD ooooffff ffffiiiilllleeee''''ssss oooowwwwnnnneeeerrrr rrrrddddeeeevvvv tttthhhheeee ddddeeeevvvviiiicccceeee iiiiddddeeeennnnttttiiiiffffiiiieeeerrrr ((((ssssppppeeeecccciiiiaaaallll ffffiiiilllleeeessss oooonnnnllllyyyy)))) ssssiiiizzzzeeee ttttoooottttaaaallll ssssiiiizzzzeeee ooooffff ffffiiiilllleeee,,,, iiiinnnn bbbbyyyytttteeeessss aaaattttiiiimmmmeeee llllaaaasssstttt aaaacccccccceeeessssssss ttttiiiimmmmeeee ssssiiiinnnncccceeee tttthhhheeee eeeeppppoooocccchhhh mmmmttttiiiimmmmeeee llllaaaasssstttt mmmmooooddddiiiiffffyyyy ttttiiiimmmmeeee ssssiiiinnnncccceeee tttthhhheeee eeeeppppoooocccchhhh ccccttttiiiimmmmeeee iiiinnnnooooddddeeee cccchhhhaaaannnnggggeeee ttttiiiimmmmeeee ((((NNNNOOOOTTTT ccccrrrreeeeaaaattttiiiioooonnnn ttttyyyyppppeeee!!!!)))) ssssiiiinnnncccceeee tttthhhheeee eeeeppppoooocccchhhh bbbbllllkkkkssssiiiizzzzeeee pppprrrreeeeffffeeeerrrrrrrreeeedddd bbbblllloooocccckkkkssssiiiizzzzeeee ffffoooorrrr ffffiiiilllleeee ssssyyyysssstttteeeemmmm IIII////OOOO bbbblllloooocccckkkkssss aaaaccccttttuuuuaaaallll nnnnuuuummmmbbbbeeeerrrr ooooffff bbbblllloooocccckkkkssss aaaallllllllooooccccaaaatttteeeedddd (The epoch was at 00:00 January 1, 1970 GMT.) If stat is passed the special filehandle consisting of an underline, no stat is done, but the current contents of the stat structure from the last stat or filetest are returned. Example: iiiiffff ((((----xxxx $$$$ffffiiiilllleeee &&&&&&&& (((((((($$$$dddd)))) ==== ssssttttaaaatttt((((____)))))))) &&&&&&&& $$$$dddd <<<< 0000)))) {{{{ pppprrrriiiinnnntttt """"$$$$ffffiiiilllleeee iiiissss eeeexxxxeeeeccccuuuuttttaaaabbbblllleeee NNNNFFFFSSSS ffffiiiilllleeee\\\\nnnn"""";;;; }}}} (This only works on machines for which the device number is negative under NFS.) study SCALAR study Takes extra time to study SCALAR ($_ if unspecified) in anticipation of doing many pattern matches on the string before it is next modified. This may or may not save time, depending on the nature and number of patterns you are searching on, and on the distribution of character frequencies in the string to be searched--you probably want to compare runtimes with and without it to see which runs faster. Those loops which scan for many short constant strings (including the constant parts of more complex patterns) will benefit most. You may have only one study active at a time--if you study a different scalar the first is "unstudied". (The way study works is this: a linked list of every character in the string to be searched is made, so we know, for example, where all the 'k' characters are. From each search string, the rarest character is selected, based on some static frequency tables constructed from some C programs and English text. Only those places that contain this "rarest" character are examined.) For example, here is a loop which inserts index 16/Feb/96 perl 5.002 with 58 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) producing entries before any line containing a certain pattern: wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ ssssttttuuuuddddyyyy;;;; pppprrrriiiinnnntttt """"....IIIIXXXX ffffoooooooo\\\\nnnn"""" iiiiffff ////\\\\bbbbffffoooooooo\\\\bbbb////;;;; pppprrrriiiinnnntttt """"....IIIIXXXX bbbbaaaarrrr\\\\nnnn"""" iiiiffff ////\\\\bbbbbbbbaaaarrrr\\\\bbbb////;;;; pppprrrriiiinnnntttt """"....IIIIXXXX bbbblllluuuurrrrffffllll\\\\nnnn"""" iiiiffff ////\\\\bbbbbbbblllluuuurrrrffffllll\\\\bbbb////;;;; ............ pppprrrriiiinnnntttt;;;; }}}} In searching for /\bfoo\b/, only those locations in $$$$____ that contain "f" will be looked at, because "f" is rarer than "o". In general, this is a big win except in pathological cases. The only question is whether it saves you more time than it took to build the linked list in the first place. Note that if you have to look for strings that you don't know till runtime, you can build an entire loop as a string and eval that to avoid recompiling all your patterns all the time. Together with undefining $/ to input entire files as one record, this can be very fast, often faster than specialized programs like _f_g_r_e_p(1). The following scans a list of files (@files) for a list of words (@words), and prints out the names of those files that contain a match: $$$$sssseeeeaaaarrrrcccchhhh ==== ''''wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ ssssttttuuuuddddyyyy;;;;'''';;;; ffffoooorrrreeeeaaaacccchhhh $$$$wwwwoooorrrrdddd ((((@@@@wwwwoooorrrrddddssss)))) {{{{ $$$$sssseeeeaaaarrrrcccchhhh ....==== """"++++++++\\\\$$$$sssseeeeeeeennnn{{{{\\\\$$$$AAAARRRRGGGGVVVV}}}} iiiiffff ////\\\\\\\\bbbb$$$$wwwwoooorrrrdddd\\\\\\\\bbbb////;;;;\\\\nnnn"""";;;; }}}} $$$$sssseeeeaaaarrrrcccchhhh ....==== """"}}}}"""";;;; @@@@AAAARRRRGGGGVVVV ==== @@@@ffffiiiilllleeeessss;;;; uuuunnnnddddeeeeffff $$$$////;;;; eeeevvvvaaaallll $$$$sssseeeeaaaarrrrcccchhhh;;;; #### tttthhhhiiiissss ssssccccrrrreeeeaaaammmmssss $$$$//// ==== """"\\\\nnnn"""";;;; #### ppppuuuutttt bbbbaaaacccckkkk ttttoooo nnnnoooorrrrmmmmaaaallll iiiinnnnppppuuuutttt ddddeeeelllliiiimmmm ffffoooorrrreeeeaaaacccchhhh $$$$ffffiiiilllleeee ((((ssssoooorrrrtttt kkkkeeeeyyyyssss((((%%%%sssseeeeeeeennnn)))))))) {{{{ pppprrrriiiinnnntttt $$$$ffffiiiilllleeee,,,, """"\\\\nnnn"""";;;; }}}} sub BLOCK sub NAME sub NAME BLOCK This is subroutine definition, not a real function _p_e_r _s_e. With just a NAME (and possibly prototypes), it's just a forward declaration. Without a NAME, it's an anonymous function declaration, and does actually return a value: the 16/Feb/96 perl 5.002 with 59 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) CODE ref of the closure you just created. See the _p_e_r_l_s_u_b manpage and the _p_e_r_l_r_e_f manpage for details. substr EXPR,OFFSET,LEN substr EXPR,OFFSET Extracts a substring out of EXPR and returns it. First character is at offset 0, or whatever you've set $[ to. If OFFSET is negative, starts that far from the end of the string. If LEN is omitted, returns everything to the end of the string. If LEN is negative, leaves that many characters off the end of the string. You can use the _s_u_b_s_t_r_(_) function as an lvalue, in which case EXPR must be an lvalue. If you assign something shorter than LEN, the string will shrink, and if you assign something longer than LEN, the string will grow to accommodate it. To keep the string the same length you may need to pad or chop your value using _s_p_r_i_n_t_f_(_). symlink OLDFILE,NEWFILE Creates a new filename symbolically linked to the old filename. Returns 1 for success, 0 otherwise. On systems that don't support symbolic links, produces a fatal error at run time. To check for that, use eval: $$$$ssssyyyymmmmlllliiiinnnnkkkk____eeeexxxxiiiissssttttssss ==== ((((eeeevvvvaaaallll ''''ssssyyyymmmmlllliiiinnnnkkkk(((("""""""",,,,""""""""))));;;;'''',,,, $$$$@@@@ eeeeqqqq ''''''''))));;;; syscall LIST Calls the system call specified as the first element of the list, passing the remaining elements as arguments to the system call. If unimplemented, produces a fatal error. The arguments are interpreted as follows: if a given argument is numeric, the argument is passed as an int. If not, the pointer to the string value is passed. You are responsible to make sure a string is pre-extended long enough to receive any result that might be written into a string. If your integer arguments are not literals and have never been interpreted in a numeric context, you may need to add 0 to them to force them to look like numbers. rrrreeeeqqqquuuuiiiirrrreeee ''''ssssyyyyssssccccaaaallllllll....pppphhhh'''';;;; #### mmmmaaaayyyy nnnneeeeeeeedddd ttttoooo rrrruuuunnnn hhhh2222pppphhhh ssssyyyyssssccccaaaallllllll((((&&&&SSSSYYYYSSSS____wwwwrrrriiiitttteeee,,,, ffffiiiilllleeeennnnoooo((((SSSSTTTTDDDDOOOOUUUUTTTT)))),,,, """"hhhhiiii tttthhhheeeerrrreeee\\\\nnnn"""",,,, 9999))));;;; Note that Perl only supports passing of up to 14 arguments to your system call, which in practice 16/Feb/96 perl 5.002 with 60 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) should usually suffice. sysopen FILEHANDLE,FILENAME,MODE sysopen FILEHANDLE,FILENAME,MODE,PERMS Opens the file whose filename is given by FILENAME, and associates it with FILEHANDLE. If FILEHANDLE is an expression, its value is used as the name of the real filehandle wanted. This function calls the underlying operating system's ooooppppeeeennnn function with the parameters FILENAME, MODE, PERMS. The possible values and flag bits of the MODE parameter are system-dependent; they are available via the standard module FFFFccccnnnnttttllll. However, for historical reasons, some values are universal: zero means read-only, one means write-only, and two means read/write. If the file named by FILENAME does not exist and the ooooppppeeeennnn call creates it (typically because MODE includes the O_CREAT flag), then the value of PERMS specifies the permissions of the newly created file. If PERMS is omitted, the default value is 0666, which allows read and write for all. This default is reasonable: see uuuummmmaaaasssskkkk. sysread FILEHANDLE,SCALAR,LENGTH,OFFSET sysread FILEHANDLE,SCALAR,LENGTH Attempts to read LENGTH bytes of data into variable SCALAR from the specified FILEHANDLE, using the system call _r_e_a_d(2). It bypasses stdio, so mixing this with other kinds of reads may cause confusion. Returns the number of bytes actually read, or undef if there was an error. SCALAR will be grown or shrunk to the length actually read. An OFFSET may be specified to place the read data at some other place than the beginning of the string. system LIST Does exactly the same thing as "exec LIST" except that a fork is done first, and the parent process waits for the child process to complete. Note that argument processing varies depending on the number of arguments. The return value is the exit status of the program as returned by the _w_a_i_t_(_) call. To get the actual exit value divide by 256. See also the eeeexxxxeeeecccc entry elsewhere in this document. This is _N_O_T what you want to use to capture the output from a command, for that you should merely use backticks, as described in the 16/Feb/96 perl 5.002 with 61 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) section on _`_S_T_R_I_N_G_` in the _p_e_r_l_o_p manpage. syswrite FILEHANDLE,SCALAR,LENGTH,OFFSET syswrite FILEHANDLE,SCALAR,LENGTH Attempts to write LENGTH bytes of data from variable SCALAR to the specified FILEHANDLE, using the system call _w_r_i_t_e(2). It bypasses stdio, so mixing this with prints may cause confusion. Returns the number of bytes actually written, or undef if there was an error. An OFFSET may be specified to get the write data from some other place than the beginning of the string. tell FILEHANDLE tell Returns the current file position for FILEHANDLE. FILEHANDLE may be an expression whose value gives the name of the actual filehandle. If FILEHANDLE is omitted, assumes the file last read. telldir DIRHANDLE Returns the current position of the _r_e_a_d_d_i_r_(_) routines on DIRHANDLE. Value may be given to _s_e_e_k_d_i_r_(_) to access a particular location in a directory. Has the same caveats about possible directory compaction as the corresponding system library routine. tie VARIABLE,CLASSNAME,LIST This function binds a variable to a package class that will provide the implementation for the variable. VARIABLE is the name of the variable to be enchanted. CLASSNAME is the name of a class implementing objects of correct type. Any additional arguments are passed to the "new" method of the class (meaning TIESCALAR, TIEARRAY, or TIEHASH). Typically these are arguments such as might be passed to the _d_b_m___o_p_e_n_(_) function of C. The object returned by the "new" method is also returned by the _t_i_e_(_) function, which would be useful if you want to access other methods in CLASSNAME. Note that functions such as _k_e_y_s_(_) and _v_a_l_u_e_s_(_) may return huge array values when used on large objects, like DBM files. You may prefer to use the _e_a_c_h_(_) function to iterate over such. Example: 16/Feb/96 perl 5.002 with 62 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) #### pppprrrriiiinnnntttt oooouuuutttt hhhhiiiissssttttoooorrrryyyy ffffiiiilllleeee ooooffffffffsssseeeettttssss uuuusssseeee NNNNDDDDBBBBMMMM____FFFFiiiilllleeee;;;; ttttiiiieeee((((%%%%HHHHIIIISSSSTTTT,,,, NNNNDDDDBBBBMMMM____FFFFiiiilllleeee,,,, ''''////uuuussssrrrr////lllliiiibbbb////nnnneeeewwwwssss////hhhhiiiissssttttoooorrrryyyy'''',,,, 1111,,,, 0000))));;;; wwwwhhhhiiiilllleeee (((((((($$$$kkkkeeeeyyyy,,,,$$$$vvvvaaaallll)))) ==== eeeeaaaacccchhhh %%%%HHHHIIIISSSSTTTT)))) {{{{ pppprrrriiiinnnntttt $$$$kkkkeeeeyyyy,,,, '''' ==== '''',,,, uuuunnnnppppaaaacccckkkk((((''''LLLL'''',,,,$$$$vvvvaaaallll)))),,,, """"\\\\nnnn"""";;;; }}}} uuuunnnnttttiiiieeee((((%%%%HHHHIIIISSSSTTTT))));;;; A class implementing an associative array should have the following methods: TTTTIIIIEEEEHHHHAAAASSSSHHHH ccccllllaaaassssssssnnnnaaaammmmeeee,,,, LLLLIIIISSSSTTTT DDDDEEEESSSSTTTTRRRROOOOYYYY tttthhhhiiiissss FFFFEEEETTTTCCCCHHHH tttthhhhiiiissss,,,, kkkkeeeeyyyy SSSSTTTTOOOORRRREEEE tttthhhhiiiissss,,,, kkkkeeeeyyyy,,,, vvvvaaaalllluuuueeee DDDDEEEELLLLEEEETTTTEEEE tttthhhhiiiissss,,,, kkkkeeeeyyyy EEEEXXXXIIIISSSSTTTTSSSS tttthhhhiiiissss,,,, kkkkeeeeyyyy FFFFIIIIRRRRSSSSTTTTKKKKEEEEYYYY tttthhhhiiiissss NNNNEEEEXXXXTTTTKKKKEEEEYYYY tttthhhhiiiissss,,,, llllaaaassssttttkkkkeeeeyyyy A class implementing an ordinary array should have the following methods: TTTTIIIIEEEEAAAARRRRRRRRAAAAYYYY ccccllllaaaassssssssnnnnaaaammmmeeee,,,, LLLLIIIISSSSTTTT DDDDEEEESSSSTTTTRRRROOOOYYYY tttthhhhiiiissss FFFFEEEETTTTCCCCHHHH tttthhhhiiiissss,,,, kkkkeeeeyyyy SSSSTTTTOOOORRRREEEE tttthhhhiiiissss,,,, kkkkeeeeyyyy,,,, vvvvaaaalllluuuueeee [[[[ooootttthhhheeeerrrrssss TTTTBBBBDDDD]]]] A class implementing a scalar should have the following methods: TTTTIIIIEEEESSSSCCCCAAAALLLLAAAARRRR ccccllllaaaassssssssnnnnaaaammmmeeee,,,, LLLLIIIISSSSTTTT DDDDEEEESSSSTTTTRRRROOOOYYYY tttthhhhiiiissss FFFFEEEETTTTCCCCHHHH tttthhhhiiiissss,,,, SSSSTTTTOOOORRRREEEE tttthhhhiiiissss,,,, vvvvaaaalllluuuueeee Unlike _d_b_m_o_p_e_n_(_), the _t_i_e_(_) function will not use or require a module for you--you need to do that explicitly yourself. See the _D_B___F_i_l_e manpage or the _C_o_n_f_i_g module for interesting _t_i_e_(_) implementations. tied VARIABLE Returns a reference to the object underlying VARIABLE (the same value that was originally returned by the _t_i_e_(_) call which bound the variable to a package.) Returns the undefined value if VARIABLE isn't tied to a package. time Returns the number of non-leap seconds since 00:00:00 UTC, January 1, 1970. Suitable for feeding to _g_m_t_i_m_e_(_) and _l_o_c_a_l_t_i_m_e_(_). 16/Feb/96 perl 5.002 with 63 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) times Returns a four-element array giving the user and system times, in seconds, for this process and the children of this process. (((($$$$uuuusssseeeerrrr,,,,$$$$ssssyyyysssstttteeeemmmm,,,,$$$$ccccuuuusssseeeerrrr,,,,$$$$ccccssssyyyysssstttteeeemmmm)))) ==== ttttiiiimmmmeeeessss;;;; tr/// The translation operator. See the _p_e_r_l_o_p manpage. truncate FILEHANDLE,LENGTH truncate EXPR,LENGTH Truncates the file opened on FILEHANDLE, or named by EXPR, to the specified length. Produces a fatal error if truncate isn't implemented on your system. uc EXPR Returns an uppercased version of EXPR. This is the internal function implementing the \U escape in double-quoted strings. Should respect any POSIX _s_e_t_l_o_c_a_l_e_(_) settings. ucfirst EXPR Returns the value of EXPR with the first character uppercased. This is the internal function implementing the \u escape in double-quoted strings. Should respect any POSIX _s_e_t_l_o_c_a_l_e_(_) settings. umask EXPR umask Sets the umask for the process and returns the old one. If EXPR is omitted, merely returns current umask. undef EXPR undef Undefines the value of EXPR, which must be an lvalue. Use only on a scalar value, an entire array, or a subroutine name (using "&"). (Using _u_n_d_e_f_(_) will probably not do what you expect on most predefined variables or DBM list values, so don't do that.) Always returns the undefined value. You can omit the EXPR, in which case nothing is undefined, but you still get an undefined value that you could, for instance, return from a subroutine. Examples: uuuunnnnddddeeeeffff $$$$ffffoooooooo;;;; uuuunnnnddddeeeeffff $$$$bbbbaaaarrrr{{{{''''bbbblllluuuurrrrffffllll''''}}}};;;; uuuunnnnddddeeeeffff @@@@aaaarrrryyyy;;;; uuuunnnnddddeeeeffff %%%%aaaassssssssoooocccc;;;; uuuunnnnddddeeeeffff &&&&mmmmyyyyssssuuuubbbb;;;; rrrreeeettttuuuurrrrnnnn ((((wwwwaaaannnnttttaaaarrrrrrrraaaayyyy ???? (((()))) :::: uuuunnnnddddeeeeffff)))) iiiiffff $$$$tttthhhheeeeyyyy____bbbblllleeeewwww____iiiitttt;;;; 16/Feb/96 perl 5.002 with 64 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) unlink LIST Deletes a list of files. Returns the number of files successfully deleted. $$$$ccccnnnntttt ==== uuuunnnnlllliiiinnnnkkkk ''''aaaa'''',,,, ''''bbbb'''',,,, ''''cccc'''';;;; uuuunnnnlllliiiinnnnkkkk @@@@ggggoooonnnneeeerrrrssss;;;; uuuunnnnlllliiiinnnnkkkk <<<<****....bbbbaaaakkkk>>>>;;;; Note: unlink will not delete directories unless you are superuser and the ----UUUU flag is supplied to Perl. Even if these conditions are met, be warned that unlinking a directory can inflict damage on your filesystem. Use rmdir instead. unpack TEMPLATE,EXPR Unpack does the reverse of pack: it takes a string representing a structure and expands it out into a list value, returning the array value. (In a scalar context, it merely returns the first value produced.) The TEMPLATE has the same format as in the pack function. Here's a subroutine that does substring: ssssuuuubbbb ssssuuuubbbbssssttttrrrr {{{{ llllooooccccaaaallll(((($$$$wwwwhhhhaaaatttt,,,,$$$$wwwwhhhheeeerrrreeee,,,,$$$$hhhhoooowwwwmmmmuuuucccchhhh)))) ==== @@@@____;;;; uuuunnnnppppaaaacccckkkk((((""""xxxx$$$$wwwwhhhheeeerrrreeee aaaa$$$$hhhhoooowwwwmmmmuuuucccchhhh"""",,,, $$$$wwwwhhhhaaaatttt))));;;; }}}} and then there's ssssuuuubbbb oooorrrrddddiiiinnnnaaaallll {{{{ uuuunnnnppppaaaacccckkkk((((""""cccc"""",,,,$$$$____[[[[0000]]]]))));;;; }}}} #### ssssaaaammmmeeee aaaassss oooorrrrdddd(((()))) In addition, you may prefix a field with a %<number> to indicate that you want a <number>-bit checksum of the items instead of the items themselves. Default is a 16-bit checksum. For example, the following computes the same number as the System V sum program: wwwwhhhhiiiilllleeee ((((<<<<>>>>)))) {{{{ $$$$cccchhhheeeecccckkkkssssuuuummmm ++++==== uuuunnnnppppaaaacccckkkk((((""""%%%%11116666CCCC****"""",,,, $$$$____))));;;; }}}} $$$$cccchhhheeeecccckkkkssssuuuummmm %%%%==== 66665555555533336666;;;; The following efficiently counts the number of set bits in a bit vector: $$$$sssseeeettttbbbbiiiittttssss ==== uuuunnnnppppaaaacccckkkk((((""""%%%%33332222bbbb****"""",,,, $$$$sssseeeelllleeeeccccttttmmmmaaaasssskkkk))));;;; untie VARIABLE Breaks the binding between a variable and a package. (See _t_i_e_(_).) 16/Feb/96 perl 5.002 with 65 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) unshift ARRAY,LIST Does the opposite of a sssshhhhiiiifffftttt. Or the opposite of a ppppuuuusssshhhh, depending on how you look at it. Prepends list to the front of the array, and returns the new number of elements in the array. uuuunnnnsssshhhhiiiifffftttt((((AAAARRRRGGGGVVVV,,,, ''''----eeee'''')))) uuuunnnnlllleeeessssssss $$$$AAAARRRRGGGGVVVV[[[[0000]]]] ====~~~~ ////^^^^----////;;;; Note the LIST is prepended whole, not one element at a time, so the prepended elements stay in the same order. Use reverse to do the reverse. use Module LIST use Module Imports some semantics into the current package from the named module, generally by aliasing certain subroutine or variable names into your package. It is exactly equivalent to BBBBEEEEGGGGIIIINNNN {{{{ rrrreeeeqqqquuuuiiiirrrreeee MMMMoooodddduuuulllleeee;;;; iiiimmmmppppoooorrrrtttt MMMMoooodddduuuulllleeee LLLLIIIISSSSTTTT;;;; }}}} The BEGIN forces the require and import to happen at compile time. The require makes sure the module is loaded into memory if it hasn't been yet. The import is not a builtin--it's just an ordinary static method call into the "Module" package to tell the module to import the list of features back into the current package. The module can implement its import method any way it likes, though most modules just choose to derive their import method via inheritance from the Exporter class that is defined in the Exporter module. See the _E_x_p_o_r_t_e_r manpage. If you don't want your namespace altered, explicitly supply an empty list: uuuusssseeee MMMMoooodddduuuulllleeee (((())));;;; That is exactly equivalent to BBBBEEEEGGGGIIIINNNN {{{{ rrrreeeeqqqquuuuiiiirrrreeee MMMMoooodddduuuulllleeee;;;; }}}} Because this is a wide-open interface, pragmas (compiler directives) are also implemented this way. Currently implemented pragmas are: uuuusssseeee iiiinnnntttteeeeggggeeeerrrr;;;; uuuusssseeee ddddiiiiaaaaggggnnnnoooossssttttiiiiccccssss;;;; uuuusssseeee ssssiiiiggggttttrrrraaaapppp qqqqwwww((((SSSSEEEEGGGGVVVV BBBBUUUUSSSS))));;;; uuuusssseeee ssssttttrrrriiiicccctttt qqqqwwww((((ssssuuuubbbbssss vvvvaaaarrrrssss rrrreeeeffffssss))));;;; uuuusssseeee ssssuuuubbbbssss qqqqwwww((((aaaaffffuuuunnnncccc bbbblllluuuurrrrffffllll))));;;; 16/Feb/96 perl 5.002 with 66 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) These pseudomodules import semantics into the current block scope, unlike ordinary modules, which import symbols into the current package (which are effective through the end of the file). There's a corresponding "no" command that unimports meanings imported by use. nnnnoooo iiiinnnntttteeeeggggeeeerrrr;;;; nnnnoooo ssssttttrrrriiiicccctttt ''''rrrreeeeffffssss'''';;;; See the _p_e_r_l_m_o_d manpage for a list of standard modules and pragmas. utime LIST Changes the access and modification times on each file of a list of files. The first two elements of the list must be the NUMERICAL access and modification times, in that order. Returns the number of files successfully changed. The inode modification time of each file is set to the current time. Example of a "touch" command: ####!!!!////uuuussssrrrr////bbbbiiiinnnn////ppppeeeerrrrllll $$$$nnnnoooowwww ==== ttttiiiimmmmeeee;;;; uuuuttttiiiimmmmeeee $$$$nnnnoooowwww,,,, $$$$nnnnoooowwww,,,, @@@@AAAARRRRGGGGVVVV;;;; values ASSOC_ARRAY Returns a normal array consisting of all the values of the named associative array. (In a scalar context, returns the number of values.) The values are returned in an apparently random order, but it is the same order as either the _k_e_y_s_(_) or _e_a_c_h_(_) function would produce on the same array. See also _k_e_y_s_(_), _e_a_c_h_(_), and _s_o_r_t_(_). vec EXPR,OFFSET,BITS Treats the string in EXPR as a vector of unsigned integers, and returns the value of the bitfield specified by OFFSET. BITS specifies the number of bits that are reserved for each entry in the bit vector. This must be a power of two from 1 to 32. _v_e_c_(_) may also be assigned to, in which case parens are needed to give the expression the correct precedence as in vvvveeeecccc(((($$$$iiiimmmmaaaaggggeeee,,,, $$$$mmmmaaaaxxxx____xxxx **** $$$$xxxx ++++ $$$$yyyy,,,, 8888)))) ==== 3333;;;; Vectors created with _v_e_c_(_) can also be manipulated with the logical operators |, & and ^, which will assume a bit vector operation is desired when both operands are strings. 16/Feb/96 perl 5.002 with 67 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) To transform a bit vector into a string or array of 0's and 1's, use these: $$$$bbbbiiiittttssss ==== uuuunnnnppppaaaacccckkkk((((""""bbbb****"""",,,, $$$$vvvveeeeccccttttoooorrrr))));;;; @@@@bbbbiiiittttssss ==== sssspppplllliiiitttt((((////////,,,, uuuunnnnppppaaaacccckkkk((((""""bbbb****"""",,,, $$$$vvvveeeeccccttttoooorrrr))))))));;;; If you know the exact length in bits, it can be used in place of the *. wait Waits for a child process to terminate and returns the pid of the deceased process, or -1 if there are no child processes. The status is returned in $?. waitpid PID,FLAGS Waits for a particular child process to terminate and returns the pid of the deceased process, or -1 if there is no such child process. The status is returned in $?. If you say uuuusssseeee PPPPOOOOSSSSIIIIXXXX """"wwwwaaaaiiiitttt____hhhh"""";;;; ............ wwwwaaaaiiiittttppppiiiidddd((((----1111,,,,&&&&WWWWNNNNOOOOHHHHAAAANNNNGGGG))));;;; then you can do a non-blocking wait for any process. Non-blocking wait is only available on machines supporting either the _w_a_i_t_p_i_d(2) or _w_a_i_t_4(2) system calls. However, waiting for a particular pid with FLAGS of 0 is implemented everywhere. (Perl emulates the system call by remembering the status values of processes that have exited but have not been harvested by the Perl script yet.) wantarray Returns TRUE if the context of the currently executing subroutine is looking for a list value. Returns FALSE if the context is looking for a scalar. rrrreeeettttuuuurrrrnnnn wwwwaaaannnnttttaaaarrrrrrrraaaayyyy ???? (((()))) :::: uuuunnnnddddeeeeffff;;;; warn LIST Produces a message on STDERR just like _d_i_e_(_), but doesn't exit or on an exception. write FILEHANDLE write EXPR write Writes a formatted record (possibly multi-line) to the specified file, using the format associated with that file. By default the format for a file 16/Feb/96 perl 5.002 with 68 PERLFUNC(1) User Contributed Perl Documentation PERLFUNC(1) is the one having the same name is the filehandle, but the format for the current output channel (see the _s_e_l_e_c_t_(_) function) may be set explicitly by assigning the name of the format to the $~ variable. Top of form processing is handled automatically: if there is insufficient room on the current page for the formatted record, the page is advanced by writing a form feed, a special top-of-page format is used to format the new page header, and then the record is written. By default the top-of-page format is the name of the filehandle with "_TOP" appended, but it may be dynamically set to the format of your choice by assigning the name to the $^ variable while the filehandle is selected. The number of lines remaining on the current page is in variable $-, which can be set to 0 to force a new page. If FILEHANDLE is unspecified, output goes to the current default output channel, which starts out as STDOUT but may be changed by the sssseeeelllleeeecccctttt operator. If the FILEHANDLE is an EXPR, then the expression is evaluated and the resulting string is used to look up the name of the FILEHANDLE at run time. For more on formats, see the _p_e_r_l_f_o_r_m manpage. Note that write is _N_O_T the opposite of read. Unfortunately. y/// The translation operator. See the section on _t_r_/_/_/ in the _p_e_r_l_o_p manpage. 16/Feb/96 perl 5.002 with 69