Perl starter for iterating over a file from either a supplied filename or stdin

gistfile1.txt

#!/usr/bin/perl -w

use strict;

my $input = *STDIN;
if(scalar @ARGV) {
  open(FH,$ARGV[0]);
  $input = *FH;
}

my $indentLevel=0;

while (<$input>)
{
    chomp;
    my $line = $_;
    print "$line \n";

}