#!/usr/bin/perl -w
use strict;

use File::Basename;

print "Please enter a filename: ";
chomp(my $old_name = <STDIN>);

my $dirname = dirname $old_name;
my $basename = basename $old_name;

$basename =~ s/^/not/;
my $new_name = "$dirname/$basename";
rename ($old_name, $new_name)
  or warn "Can't rename '$old_name' to '$new_name': $!"; 

##</code><code>##

#!/usr/bin/perl -w
use strict;

use File::Basename;
use File::Spec;

print "Please enter a filename: ";
chomp(my $old_name = <STDIN>);

my $dirname = dirname $old_name;
my $basename = basename $old_name;

$basename =~ s/^/not/;
my $new_name = File::Spec->catfile($dirname, $basename);

rename ($old_name, $new_name)
  or warn "Can't rename '$old_name' to '$new_name': $!";