Example 6.13: urlify

#!/usr/bin/perl # urlify - wrap HTML links around URL-like constructs  $urls = '(http|telnet|gopher|file|wais|ftp)'; $ltrs = '\w'; $gunk = '/#~:.?+=&%@!\-'; $punc = '.:?\-'; $any  = "${ltrs}${gunk}${punc}";  while (<>) {     s{       \b                    # start at word boundary       (                     # begin $1  {        $urls     :          # need resource and a colon        [$any] +?            # followed by on or more                             #  of any valid character, but                             #  be conservative and take only                             #  what you need to....       )                     # end   $1  }       (?=                   # look-ahead non-consumptive assertion        [$punc]*             # either 0 or more punctuation        [^$any]              #   followed by a non-url char        |                    # or else        $                    #   then end of the string       )      }{<A HREF="$1">$1</A>}igox;     print; }