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TR(1L) TR(1L) NNAAMMEE tr - translate or delete characters SSYYNNOOPPSSIISS ttrr [-cst] [--complement] [--squeeze-repeats] [--trun- cate-set1] string1 string2 ttrr {-s,--squeeze-repeats} [-c] [--complement] string1 ttrr {-d,--delete} [-c] string1 ttrr {-d,--delete} {-s,--squeeze-repeats} [-c] [--comple- ment] string1 string2 GNU ttrr also accepts the --help and --version options. DDEESSCCRRIIPPTTIIOONN This manual page documents the GNU version of ttrr.. ttrr copies the standard input to the standard output, perform- ing one of the following operations: +o translate, and optionally squeeze repeated char- acters in the result +o squeeze repeated characters +o delete characters +o delete characters, then squeeze repeated charac- ters from the result. The _s_t_r_i_n_g_1 and (if given) _s_t_r_i_n_g_2 arguments define ordered sets of characters, referred to below as set1 and set2. These sets are the characters of the input that ttrr operates on. The _-_-_c_o_m_p_l_e_m_e_n_t (_-_c) option replaces set1 with its complement (all of the characters that are not in set1). SSPPEECCIIFFYYIINNGG SSEETTSS OOFF CCHHAARRAACCTTEERRSS The format of the _s_t_r_i_n_g_1 and _s_t_r_i_n_g_2 arguments resembles the format of regular expressions; however, they are not regular expressions, only lists of characters. Most char- acters simply represent themselves in these strings, but the strings can contain the shorthands listed below, for convenience. Some of them can be used only in _s_t_r_i_n_g_1 or _s_t_r_i_n_g_2, as noted below. Backslash escapes. A backslash followed by a character not listed below causes an error message. \a Control-G. \b Control-H. \f Control-L. \n Control-J. \r Control-M. FSF GNU Text Utilities 1 TR(1L) TR(1L) \t Control-I. \v Control-K. \ooo The character with the value given by _o_o_o, which is 1 to 3 octal digits. \\ A backslash. Ranges. The notation `_m-_n' expands to all of the charac- ters from _m through _n, in ascending order. _m should col- late before _n; if it doesn't, an error results. As an example, `0-9' is the same as `0123456789'. Although GNU ttrr does not support the System V syntax that uses square brackets to enclose ranges, translations specified in that format will still work as long as the brackets in string1 correspond to identical brackets in string2. Repeated characters. The notation `[_c*_n]' in _s_t_r_i_n_g_2 expands to _n copies of character _c. Thus, `[y*6]' is the same as `yyyyyy'. The notation `[_c*]' in _s_t_r_i_n_g_2 expands to as many copies of _c as are needed to make set2 as long as set1. If _n begins with a 0, it is interpreted in octal, otherwise in decimal. Character classes. The notation `[:_c_l_a_s_s_-_n_a_m_e:]' expands to all of the characters in the (predefined) class named _c_l_a_s_s_-_n_a_m_e. The characters expand in no particular order, except for the `upper' and `lower' classes, which expand in ascending order. When the _-_-_d_e_l_e_t_e (_-_d) and _-_-_s_q_u_e_e_z_e_-_r_e_p_e_a_t_s (_-_s) options are both given, any charac- ter class can be used in _s_t_r_i_n_g_2. Otherwise, only the character classes `lower' and `upper' are accepted in _s_t_r_i_n_g_2, and then only if the corresponding character class (`upper' and `lower', respectively) is specified in the same relative position in _s_t_r_i_n_g_1. Doing this speci- fies case conversion. The class names are given below; an error results when an invalid class name is given. alnum Letters and digits. alpha Letters. blank Horizontal whitespace. cntrl Control characters. digit Digits. graph Printable characters, not including space. lower Lowercase letters. print Printable characters, including space. FSF GNU Text Utilities 2 TR(1L) TR(1L) punct Punctuation characters. space Horizontal or vertical whitespace. upper Uppercase letters. xdigit Hexadecimal digits. Equivalence classes. The syntax `[=_c=]' expands to all of the characters that are equivalent to _c, in no particular order. Equivalence classes are a recent invention intended to support non-English alphabets. But there seems to be no standard way to define them or determine their contents. Therefore, they are not fully implemented in GNU ttrr; each character's equivalence class consists only of that character, which makes this a useless con- struction currently. TTRRAANNSSLLAATTIINNGG ttrr performs translation when _s_t_r_i_n_g_1 and _s_t_r_i_n_g_2 are both given and the --delete (_-_d) option is not given. ttrr translates each character of its input that is in set1 to the corresponding character in set2. Characters not in set1 are passed through unchanged. When a character appears more than once in set1 and the corresponding char- acters in set2 are not all the same, only the final one is used. For example, these two commands are equivalent: tr aaa xyz tr a z A common use of ttrr is to convert lowercase characters to uppercase. This can be done in many ways. Here are three of them: tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ tr a-z A-Z tr '[:lower:]' '[:upper:]' When ttrr is performing translation, set1 and set2 should normally have the same length. If set1 is shorter than set2, the extra characters at the end of set2 are ignored. On the other hand, making set1 longer than set2 is not portable; POSIX.2 says that the result is undefined. In this situation, the BSD ttrr pads set2 to the length of set1 by repeating the last character of set2 as many times as necessary. The System V ttrr truncates set1 to the length of set2. By default, GNU ttrr handles this case like the BSD ttrr does. When the --truncate-set1 (_-_t) option is given, GNU ttrr han- dles this case like the System V ttrr instead. This option is ignored for operations other than translation. Acting like the System V ttrr in this case breaks the FSF GNU Text Utilities 3 TR(1L) TR(1L) relatively common BSD idiom: tr -cs A-Za-z0-9 '\012' because it converts only zero bytes (the first element in the complement of set1), rather than all non- alphanumerics, to newlines. SSQQUUEEEEZZIINNGG RREEPPEEAATTSS AANNDD DDEELLEETTIINNGG When given just the --delete (_-_d) option, ttrr removes any input characters that are in set1. When given just the --squeeze-repeats (_-_s) option, ttrr replaces each input sequence of a repeated character that is in set1 with a single occurrence of that character. When given both the --delete and the --squeeze-repeats options, ttrr first performs any deletions using set1, then squeezes repeats from any remaining characters using set2. The --squeeze-repeats option may also be used when trans- lating, in which case ttrr first performs translation, then squeezes repeats from any remaining characters using set2. Here are some examples to illustrate various combinations of options: Remove all zero bytes: tr -d '\000' Put all words on lines by themselves. This converts all non-alphanumeric characters to newlines, then squeezes each string of repeated newlines into a single newline: tr -cs '[a-zA-Z0-9]' '[\n*]' Convert each sequence of repeated newlines to a single newline: tr -s '\n' GNU ttrr also accepts the following options in any combina- tion with the others. _-_-_h_e_l_p Print a usage message and exit with a non-zero sta- tus. _-_-_v_e_r_s_i_o_n Print version information on standard error then exit. WWAARRNNIINNGG MMEESSSSAAGGEESS Setting the environment variable POSIXLY_CORRECT turns off several warning and error messages, for strict compliance with POSIX.2. The messages normally occur in the follow- ing circumstances: 1. When the _-_-_d_e_l_e_t_e option is given but FSF GNU Text Utilities 4 TR(1L) TR(1L) _-_-_s_q_u_e_e_z_e_-_r_e_p_e_a_t_s is not, and _s_t_r_i_n_g_2 is given, GNU ttrr by default prints a usage message and exits, because _s_t_r_i_n_g_2 would not be used. The POSIX specification says that _s_t_r_i_n_g_2 must be ignored in this case. Silently ignoring arguments is a bad idea. 2. When an ambiguous octal escape is given. For example, \400 is actually \40 followed by the digit 0, because the value 400 octal does not fit into a single byte. Note that GNU ttrr does not provide complete BSD or System V compatibility. For example, there is no option to disable interpretation of the POSIX constructs [:alpha:], [=c=], and [c*10]. Also, GNU ttrr does not delete zero bytes auto- matically, unlike traditional UNIX versions, which provide no way to preserve zero bytes. FSF GNU Text Utilities 5