$tr(/<input>/<output>/<string>)

This function “translates” the input characters to the output characters in the given string. Input and output characters are paired up in the order they are specified in (first-first, second-second, etc.). If there are more input than output, the last output character will replace any input characters that do not have a corresponding output character. Any of the arguments may be variables or literal strings. The delimiter does not need to be a '/'; it may be any character not found in the input or output characters.

This function is useful for doing very simple text encoding, such as ROT13. It is also useful for stripping out unwanted characters from untrusted sources (such as shell meta characters).

“translated” string

/* assume $oldc is "aeiouy" and $newc is "yuoiea" */
$tr(/s/z/efnet has bots)             returns "efnet haz botz"
$tr(/$oldc/$newc/efnet has bots)     returns "ufnut hys bits"
$tr(/$oldc/_/efnet has bots)         returns "_fn_t h_s b_ts"
$tr(/abc//blah blah)                 effectively the same as $strip()
$tr(#a#e#blah)                       returns "bleh"