Quick line fixing with Perl

comment-lines.pl

use strict;
use warnings;

open my $in_fh, '<', $file_name;
open my $out_fh, '>', "$file_name.new";

while(<$in_fh>) {
    # Current line is stored in $_
    # if current line contains the text 'zend-extensions'...
    if ($_ =~ m/zend-extensions/) {
        # ... comment it out
        print $out_fh "; $_";
    }
    else {
        # otherwise, just pass the line unchanged
        print $out_fh $_;
    }
}

close $in_fh;
close $out_fh;
unlink $file_name;
rename "$file_name.new" => $file_name;