#!/usr/bin/perl -pi.orig
    s/foo/bar/;
##</code><code>##

    #!/usr/bin/perl
    $extension = '.orig';
    LINE: while (<>) {
	if ($ARGV ne $oldargv) {
	    if ($extension !~ /\*/) {
		$backup = $ARGV . $extension;
	    }
	    else {
		($backup = $extension) =~ s/\*/$ARGV/g;
	    }
	    rename($ARGV, $backup);
	    open(ARGVOUT, ">$ARGV");
	    select(ARGVOUT);
	    $oldargv = $ARGV;
	}
	s/foo/bar/;
    }
    continue {
	print;	# this prints to original filename
    }
    select(STDOUT);
##</code><code>##

#!/usr/bin/perl

$file="test";
$cmd="perl -pi -e s\'\/^\\s+\/\/'g $file";
print "$cmd\n";
system($cmd);

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

$file="test";
$cmd="perl -pi -e s\'\/^\\s+\/\/'g $file";
print "$cmd\n";
system($cmd);