NAME

tr − translate characters

SYNOPSIS

tr [ −cds ] [ string1 [ string2 ] ]

DESCRIPTION

Tr copies the standard input to the standard output with substitution or deletion of selected characters.  Input characters found in string1 are mapped into the corresponding characters of string2. Any combination of the options −cds may be used:

−c Complements the set of characters in string1 with respect to the universe of characters whose ASCII codes are 001 through 377 octal. 

−d Deletes all input characters in string1.

−s Squeezes all strings of repeated output characters that are in string2 to single characters. 

The following abbreviation conventions may be used to introduce ranges of characters or repeated characters into the strings:

[a−z] Stands for the string of characters whose ASCII codes run from character a to character z, inclusive. 

[a∗n] Stands for n repetitions of a.  If the first digit of n is 0, n is considered octal; otherwise, n is taken to be decimal.  A zero or missing n is taken to be huge; this facility is useful for padding string2.

The escape character \ may be used as in the shell to remove special meaning from any character in a string.  In addition, \ followed by 1, 2, or 3 octal digits stands for the character whose ASCII code is given by those digits. 

EXAMPLE

tr −cs "[A−Z][a−z]" "[\012∗]" <file1 >file2

creates a list of all the words in "file1" one per line in "file2", where a word is taken to be a maximal string of alphabetics.  The strings are quoted to protect the special characters from interpretation by the shell; 012 is the ASCII code for newline. 

In this case, tr has substituted the newline character for all the alphabetics in "file1", reconstituted the alphabetics with the −c option, squeezed the newlines to one per occurrence, with the −s option, and directed the output to "file2". 

SEE ALSO

ed(1), sh(1), ascii(5). 

BUGS

Won’t handle ASCII NUL in string1 or string2; always deletes NUL from input. 

Version 2.3  —  July 04, 1985