1 #!/usr/bin/perl
 2 use warnings;
 3 use strict;
 4 
 5 my $pattern=$ARGV[0];
 6 if(not $pattern){
 7     print "Usage: ./ret.pl PATTERN\n";
 8     exit;
 9 }
10 print "The pattern is m{$pattern}.\n";
11 print "Ctrl + D to exit.\n";
12 print ">";
13 while(<STDIN>){
14     chomp(my $line = $_);
15     if($line =~ m{$pattern}){
16         print "matched: '$`<$&>$''.\n";
17     } else {
18         print "not matched.\n";
19     }
20     print ">";
21 }