replace 's/this/that/g' 1.txt 2.txt 3.txt 4.txt

#!/usr/local/bin/perl
#
# Replaces a string within multiple files
# specified on the command line

$mv = '/bin/mv';

$op = shift || die("Usage: $0 perlexpr [filenames]\n");

if (!@ARGV) {
  @ARGV = <STDIN>;
  chop(@ARGV);

exec(PATH_TO_THE_PROGRAM);
$result = system(PATH_TO_THE_PROGRAM);

#!/usr/bin/perl

# get logged-in user name
print "Current user is " . getlogin();

perl -le 'print scalar getpwuid $<'

#!/usr/bin/perl -w

use strict;

open (COMMON,"common.txt") or die $!;
open (IMAGE,">image.txt") or die $!;
open (HTML,">html.txt") or die $!;
my @commonFile = <COMMON>;
print IMAGE grep(/\.(jpg|bmp)$/, @commonFile);