Usage: /usr/bin/tr [OPTION]... STRING1 [STRING2] Translate, squeeze, and/or delete characters from standard input, writing to standard output. STRING1 and STRING2 specify arrays of characters ARRAY1 and ARRAY2 that control the action. -c, -C, --complement use the complement of ARRAY1 -d, --delete delete characters in ARRAY1, do not translate -s, --squeeze-repeats replace each sequence of a repeated character that is listed in the last specified ARRAY, with a single occurrence of that character -t, --truncate-set1 first truncate ARRAY1 to length of ARRAY2 --help display this help and exit --version output version information and exit ARRAYs are specified as strings of characters. Most represent themselves. Interpreted sequences are: \NNN character with octal value NNN (1 to 3 octal digits) \\ backslash \a audible BEL \b backspace \f form feed \n new line \r return \t horizontal tab \v vertical tab CHAR1-CHAR2 all characters from CHAR1 to CHAR2 in ascending order [CHAR*] in ARRAY2, copies of CHAR until length of ARRAY1 [CHAR*REPEAT] REPEAT copies of CHAR, REPEAT octal if starting with 0 [:alnum:] all letters and digits [:alpha:] all letters [:blank:] all horizontal whitespace [:cntrl:] all control characters [:digit:] all digits [:graph:] all printable characters, not including space [:lower:] all lower case letters [:print:] all printable characters, including space [:punct:] all punctuation characters [:space:] all horizontal or vertical whitespace [:upper:] all upper case letters [:xdigit:] all hexadecimal digits [=CHAR=] all characters which are equivalent to CHAR Translation occurs if -d is not given and both STRING1 and STRING2 appear. -t is only significant when translating. ARRAY2 is extended to length of ARRAY1 by repeating its last character as necessary. Excess characters of ARRAY2 are ignored. Character classes expand in unspecified order; while translating, '[:lower:]' and '[:upper:]' may be used in pairs to specify case conversion. Squeezing occurs after translation or deletion. Arguments like '[...]' should be quoted, to avoid potential shell globbing. Report bugs to: . GNU coreutils home page: General help using GNU software: Full documentation or available locally via: info '(coreutils) tr invocation'