#!/usr/bin/perl
use warnings;
use strict;

use File::Copy;

my($fileName) = $ARGV[0];
print("$fileName \n");

my($find) = "cps***";
my($replace) = "nat***";


if(-e $ARGV[0])
{
        my($copy) = "$ARGV[0].bak";
        copy($ARGV[0], $copy) or die "File cannot be copied. \n";
}
                       

else
{
    print "File does not exist. \n";
    exit;
}

open(INPUT,"$copy") or die 'Cannot open file: $!\n';
open(OUTPUT,">$ARGV[0]");

while(<INPUT>){
    $_ =~ s/$find/$replace/g;
    print OUTPUT $_;
}

close INPUT;
close OUTPUT;
unlink($copy);

print("File $fileName correctly pointed\n");

exit 0;

##</code><code>##

Variable "$copy" is not imported at /home/test/.put_on_nat.pl line 25.
	(Did you mean &copy instead?)
Variable "$copy" is not imported at /home/test/.put_on_nat.pl line 35.
	(Did you mean &copy instead?)
Global symbol "$copy" requires explicit package name at /home/test/.put_on_nat.pl line 25.
Global symbol "$copy" requires explicit package name at /home/test/.put_on_nat.pl line 35.

##</code><code>##

"my" variable $copy masks earlier declaration in same scope at /home/test/.put_on_nat.pl line 35.
Can't declare string in "my" at /home/test/.put_on_nat.pl line 25, near ")) "