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Text File | 1992-06-24 | 20.2 KB | 503 lines

_l_e_s_s - _o_p_p_o_s_i_t_e _o_f _m_o_r_e Version 1.4Z June 14, 1991 Versions since Amiga version 1.3Z are supported by Raymond L. Zarling, Department of Computer Science Calif. State Univ. Stanislaus Turlock, CA 95380 rayz@csustan.EDU _l_e_s_s [-_d_s_t_w_c_C_e_E_m_M_q_Q_u_U] [-_h_N] [-b[fp]_N] [-x_N] [-[z]_N] [-_P[_m_M]_s_t_r_i_n_g] [+_c_m_d] [_f_i_l_e_n_a_m_e]... _L_e_s_s is a program similar to _m_o_r_e (1), but which allows backwards movement in the file as well as forward movement. Also, _l_e_s_s does not have to read the entire input file before starting, so with large input files it starts up fas- ter than most text editors. Commands are based on _m_o_r_e, _v_i and _e_m_a_c_s. Commands may be preceeded by a decimal number, called N in the descrip- tions below. The number is used by some commands, as indi- cated. _I_n _t_h_e _f_o_l_l_o_w_i_n_g _d_e_s_c_r_i_p_t_i_o_n_s, ^_X _m_e_a_n_s _c_o_n_t_r_o_l-_X. H or Help key Help: display a summary of these commands. If you for- get all the other commands, remember this one. SPACE Scroll forward N lines, default one window (see option -z below). If N is more than the screen size, only the final screenful is displayed. f or ^F Same as SPACE. ^V Same as SPACE. b or ^B Scroll backward N lines, default one window (see option -z below). If N is more than the screen size, only the final screenful is displayed. RETURN Scroll forward N lines, default 1. The entire N lines are displayed, even if N is more than the screen size. e or ^E Same as RETURN. ^N Same as RETURN. j or ^J Also the same as RETURN. y or ^Y Scroll backward N lines, default 1. The entire N lines are displayed, even if N is more than the screen size. k or ^K Same as y. ^P Same as y. d or ^D Scroll forward N lines, default half of the screen. If N is specified, it becomes the new default for subsequent d and u commands. The half-screen default is set again whenever the screen is resized. u or ^U Scroll backward N lines, default half of the screen. If N is specified, it becomes the new default for subsequent d and u commands. The half-screen default is set again whenever the screen is resized. r or ^R or ^L Repaint the screen. R Repaint the screen, discarding any buffered input. Useful if the file is changing while it is being viewed. g Go to line N in the file, default 1 (beginning of file). (Warning: this may be slow if N is large.) < Same as g. G Go to line N in the file, default the end of the file. (Warning: this may be slow if standard input, rather than a file, is being read.) > Same as G. p Go to a position N percent into the file. N should be between 0 and 100. (This is possible if standard input is being read, but only if _l_e_s_s has already read to the end of the file. It is always fast, but not always useful.) % Same as p. m Followed by any lowercase letter, marks the current position with that letter. ' (Single quote.) Followed by any lowercase letter, returns to the position which was previously marked with that letter. Followed by another single quote, returns to the postion at which the last "large" move- ment command was executed. All marks are lost when a new file is examined. /pattern Search forward in the file for the N-th line containing the pattern. N defaults to 1. The pattern is a regu- lar expression, as recognized by Unix _e_d (see the section on regular expressions below). The search starts at the second line displayed (but see the -t option, which changes this). If the pattern is omitted, search for another occurance of the most recent pattern. ^S Same as /. ?pattern Search backward in the file for the N-th line contain- ing the pattern. The search starts at the line immedi- ately before the top line displayed. If the pattern is omitted, search for another occurance of the most recent pattern. n Repeat previous search, for N-th line containing the last pattern, searching in the same direction as the previous search. E Examine a new file. If the filename is missing, the "current" file (see the N and P commands below) from the list of files in the command line is re-examined. If the filename is a pound sign (#), the previously examined file is re-examined (one level of backup only). N Examine the next file (from the list of files given in the command line). If a number N is specified (not to be confused with the command N), the N-th next file is examined. P Examine the previous file. If a number N is specified, the N-th previous file is examined. = or ^G Prints some information about the file being viewed, including its name and the byte offset of the bottom line being displayed. If possible, it also prints the length of the file and the percent of the file above the last displayed line. - Followed by one of the command line option letters (see below), this will toggle the setting of that option and/or print a message describing the new setting. Not all options can be set from within the program: b, P, and window sizing are command-line only options. +cmd Causes the specified cmd to be executed each time a new file is examined. For example, +G causes _l_e_s_s to ini- tially display each file starting at the end rather than the beginning. V Prints the version number of _l_e_s_s being run. q Exits _l_e_s_s. _C_o_m_m_a_n_d _l_i_n_e _o_p_t_i_o_n_s _a_r_e _d_e_s_c_r_i_b_e_d _b_e_l_o_w. _M_o_s_t _o_p_t_i_o_n_s _m_a_y _b_e _c_h_a_n_g_e_d _w_h_i_l_e _l_e_s_s is running, via the "-" command. Options are also taken from the environment variable "LESS". For example, if you like very verbose prompting, to avoid typing "less -M ..." each time _l_e_s_s is invoked, you might tell _c_s_h or the AmigaDOS shell: setenv LESS M or if you use _S_K_s_h: LESS=M; export LESS The environment variable is parsed before the command line, so command line options override the LESS environment vari- able. A dollar sign ($) may be used to signal the end of an option string. This is important only for options like -P which take a following string. Some options have values, some are 2-way toggles, and some are 3-way toggles. The 3-way ones are handled by using both an upper-case and a lower-case option name. Usually, the upper- case option is the most extreme, the lower-case setting is moderate, and neither is least extreme. For instance, the -m and -M options control the length of the prompt line. If -M is in effect, you get a relatively long prompt, while -m is much shorter. If neither -m nor -M is set, the prompt is a single ":" character (unless you redefine one or more of these using -P). To change a 3-way option, use either -x or -X, where x is the option name. Typing -x will establish the moderate case if it wasn't already set (i.e. either -X or neither was in effect) or set the least extreme ("neither") choice if it was. Similarly, -X would establish the X option if it wasn't already in effect; otherwise "neither". -b Numeric; set from command line or environment only. The -b_n option tells _l_e_s_s to use a non-standard buffer size. There are two standard (default) buffer sizes, one is used when a file is being read and the other when a pipe (standard input) is being read. The current defaults are 5 buffers for files and 12 for pipes. (Buffers are 1024 bytes.) The number _n speci- fies a different number of buffers to use. The -b may be followed by "f", in which case only the file default is changed, or by "p" in which case only the pipe default is changed. Otherwise, both are changed. This option cannot be reset using the '-' command from within Less. These default settings are pretty minimal, designed for situations where memory is really at a premium. (A full page of text on a high-res screen can be nearly 4k.) If you have enough memory, you may want to use an environment variable to revise them upward; I use -bf15bp100. -c and -C 3-way switch If the -c option is set, when _l_e_s_s needs to change the entire display, it will paint from the top line down. Otherwise, it will repaint the screen by scrolling from the bottom of the screen. The -C option is like -c, but the screen is cleared before it is repainted. This is the fastest option, and is the default upon program startup. The -c or -C option may be overridden for backward file motion by a sufficiently large setting of -h. If -h is set larger than the screen size, full page backwards movements will scroll regardless of the -C setting. -e and -E 3-way switch Under -e, the only way to exit less is via the "q" com- mand, or the screen close gadget. Without the -e option, less automatically exits if you use a page forward com- mand when you have already reached end-of-file (default). The -E flag causes less to exit if you use any of the usual commands (not just page forward) after you have reached end-of-file. Regardless of the setting of this switch, Less will quit immediately upon receipt of a BREAK signal. BREAK may be generated by the AmigaDOS "break" command directed at the Less process, or by a ^C in the invoking CLI window (if there is one). A ^C in the Less window is ignored, with a warning message. -h Numeric The -h option interacts with -c to specify under what conditions backwards scrolling will be used to update a display. The -h setting is the maximum number of lines to scroll backwards. If it is necessary to move backwards more than this many lines, or more than one screenful, the screen is repainted in a forward direction. Backwards movements of exactly one screenful are handled according to the -c setting, if the user leaves -h unset. If -h is left unspecified by the user, it defaults to one less than the screen size. Once the user specifies a value, however, that value is retained for the balance of the run. Use -h0 to disable all backwards scrolling. -m and -M 3-way switch By default, _l_e_s_s prompts verbosely (-m), with the percent into the file. The -M option causes _l_e_s_s to prompt even more verbosely than -m. If neither -m nor -M is set, the prompt is very short. Note that Less automatically shortens any prompt if the screen is not wide enough. -P String; command line or environment only The -P option provides a way to tailor the three prompt styles to your own preference. You would normally put this option in your LESS environment variable, rather than type it in with each less command. Such an option must either be the last option in the LESS variable, or be terminated by a dollar sign. -P followed by a string changes the default (short) prompt to that string. -Pm changes the medium (-m) prompt to the string, and -PM changes the long (-M) prompt. The string consists of a sequence of letters which are replaced with certain predefined strings, as follows: Ffile name ffile name, only once Ofile n of n ofile n of n, only once bbyte offset ppercent into file Ppercent if known, else byte offset Angle brackets, < and >, may be used to surround a literal string to be included in the prompt. The defaults are "fo" for the short prompt, "foP" for the medium prompt, and "Fobp" for the long prompt. Example: Setting your LESS variable to "PmFOP$PMFObp" would change the medium and long prompts to always include the file name and "file n of n" message. Another example: Setting your LESS variable to "mPm<--Less-->FoPe" would change the medium prompt to the string "--Less--" followed by the file name and percent into the file. It also selects the medium prompt as the default prompt (because of the first "m"). -q and -Q 3-way switch Normally, if an attempt is made to scroll past the end of the file or before the beginning of the file, the screen flashes ("visual bell") to indicate this fact. The -q option tells _l_e_s_s not to flash the screen at such times. Even if -q is given, _l_e_s_s will flash the screen on certain other errors, such as typing an invalid character. The -Q option tells _l_e_s_s to be quiet all the time; that is, never do the visual bell. -s 2-way switch The -s option causes consecutive blank lines to be squeezed into a single blank line. This is useful when viewing _n_r_o_f_f output. -t 2-way switch Normally, forward searches start just after the top displayed line (that is, at the second displayed line). Thus forward searches include the currently displayed screen. The -t option causes forward searches to start just after the bottom line displayed, thus skipping the currently displayed screen. -u and -U 3-way switch If the -u option is given, backspaces are treated as printable characters; that is, they are sent to the terminal when they appear in the input. If the -U option is given, backspaces are printed as the two character sequence "^H". If neither -u nor -U is given, backspaces which appear adjacent to an underscore character are treated spe- cially: the underlined text is displayed using the terminal's hardware underlining capability. Also, backspaces which appear between two identical charac- ters are treated specially: the overstruck text is printed using the terminal's hardware boldface capabil- ity. Other backspaces are deleted, along with the preceeding character. This is the default setting. The recognition of ANSI escape sequences is also controlled by this switch. The ANSI underlining, boldface, italic, and inverse rendering is only done if neither -u nor -U is set. -w 2-way switch Normally, _l_e_s_s uses a tilde character to represent lines past the end of the file. The -w option causes blank lines to be used instead. -x Numeric The -x_n option sets tab stops every _n positions. The default for _n is 8. -[z] Numeric When given a backwards or forwards window command, _l_e_s_s will by default scroll backwards or forwards one screenful of lines. The -z_n option changes the default scrolling window size to _n lines, or one screenful, whichever is smaller. Note that the "z" is optional for compatibility with _m_o_r_e. If the screen is resized so that the -z option would be larger than a screenful, -z is reset to this smaller screen size. If the screen is then enlarged to a size greater than -z, the previously specified value is restored. + String If a command line option begins with +, the remainder of that option is taken to be an initial command to _l_e_s_s. For example, +G tells _l_e_s_s to start at the end of the file rather than the beginning, and +/xyz tells it to start at the first occurence of "xyz" in the file. As a special case, +<number> acts like +<number>g; that is, it starts the display at the specified line number (however, see the caveat under the "g" command above). If the option starts with ++, the initial command applies to every file being viewed, not just the first one. The + command described previ- ously may also be used to set (or change) an initial command for every file. -[N,N,N,N] If an option of this form appears on the command line, Less uses the information to size and position its display window. Any of the four values may be omitted, defaulting to 0. If one or more of the last values is omitted, the trailing commas may be omitted also. A value of zero in either of the last two positions causes Less to use maximum screen dimensions. The four values indicate in order the left edge, top edge, width, and height of window to use. If any of these are negative, they are taken as relative to the bottom right corner of the workbench screen. Thus, -[0,12,,-100] will open a full-width window extending from 12 pixels from the top to 100 pixels from the bottom of the screen. Similarly, -[-400,0,400,0] would open a full- height window which is flush against the right edge of the screen and 400 pixels wide. If the window specified would fall off an edge of the screen, or would go less than a certain minimum size, the window is silently coerced back into conformity. _R_e_g_u_l_a_r _E_x_p_r_e_s_s_i_o_n _P_a_t_t_e_r_n _M_a_t_c_h_i_n_g Less uses Regular Expressions, in the style of Unix 'ed', for specifying searches. While these expressions can appear quite cryptic, they are very powerful tools for locating text within a document. Any pattern consisting only of letters, numbers, and spaces will simply search for the given pattern. But you can use one or more of the metacharacters [].^$()|*+ to engineer very sophisticated searches. The '.' stands for any single character, and 'x*' stands for 0 or more occurances of x (so 'x.*y' would match anything that started with x and ended with y). 'x+' works the same way, for 1 or more occurances of x. 'x?' matches 0 or 1 occurances of x (i.e. 'x' or nothing). '[abc]' matches any single occurance of 'a', 'b', or 'c'. '[^abc]' matches any single character except 'a', 'b', or 'c'. '[a-m]' matches any single character in the range 'a' through 'm' inclusive. '^x' finds x only at the beginning of a line; 'x$' only at the end of a line. 'x|y' matches either x or y. The various pieces can be combined, of course, and grouped with parentheses. For instance, '([Aa]ny|[Ee]ach) +of you' would find any phrase beginning with 'any' or 'each' (possibly capitalized) followed by one or more blanks, followed by 'of you'. ' (can)?not ' matches either 'not' or 'cannot', but not 'nothing' or 'cancel'. '[^a-zA-Z]i[^a-zA-Z]' finds all occurances of a variable 'i' in a program, but does not find 'i' embedded in other variable names or words. To match a metacharacter literally, precede it with a backslash; e.g. '\. \*' would match a period followed by two spaces and an asterisk. _O_t_h_e_r _C_o_n_s_i_d_e_r_a_t_i_o_n_s Less is residentable, so if you use it a lot you may wish to add it to your system resident list. To do this, make sure the pure bit is set in the file protection codes (protect +p Less). Then add the line "resident c:Less" (or whatever your path is) to your startup-sequence. Less uses internally Ascii characters 0 and 129-136. Since these are non-printing characters, it shouldn't make any difference under normal circumstances. Character 0 will display as '@' and 129-136 as ^?. _W_h_e_n _u_s_e_d _o_n _s_t_a_n_d_a_r_d _i_n_p_u_t (_r_a_t_h_e_r _t_h_a_n _a _f_i_l_e), _y_o_u _c_a_n _m_o_v_e _b_a_c_k_w_a_r_d_s _o_n_l_y _a _f_i_n_i_t_e _a_m_o_u_n_t, _c_o_r_r_e_s_p_o_n_d_i_n_g _t_o _t_h_a_t _p_o_r_t_i_o_n _o_f _t_h_e _f_i_l_e _w_h_i_c_h _i_s _s_t_i_l_l _b_u_f_f_e_r_e_d. _T_h_e -_b _o_p_t_i_o_n _m_a_y _b_e _u_s_e_d _t_o _e_x_p_a_n_d _t_h_e _b_u_f_f_e_r _s_p_a_c_e.