#!/usr/bin/perl -w

use strict;
use warnings;

my $file = "data.txt";       

local $^I = ".bak";
local @ARGV = ($file);
while (<>) {
chomp;
my @field = split(':');
if ($field[1] =~ s/E/L/g) {
print "$field[0]:$field[1]\n";
} elsif ($field[1] =~ s/L/E/g) {
print "$field[0]:$field[1]\n";
} else {
print "$_\n";
}
}
unlink("$file.bak");

print "UPDATED!!";

sleep 5;
exit();

__DATA__
1:E
2:L
3:L