my $drive = substr(getcwd(), 0, 2);
chdir('C:\\');
chdir($drive);

##</code><code>##

use strict;
use warnings;

use Cwd qw(getcwd chdir getdcwd);

# Here, D:\testdir exists, but C:\testdir does NOT
my $drive = substr(getcwd(), 0, 2);
chdir('C:/testdir') or die "No such directory 'C:/testdir'\n";
chdir($drive);

__END__
Produces:
No such directory 'C:/testdir'

##</code><code>##

use strict;
use warnings;

use Cwd qw(chdir getdcwd);

show_drives();
system("dir/w");
chdir("D:/testdir") or die "Can't change to dir 'D:/testdir' ($!)\n";
system("dir/w");

sub show_drives {
    printf "You are in '%s' on the current drive\n", getdcwd();
    printf "You are in '%s' on the 'D' drive\n",     getdcwd('D');
    print  "\n";
}

##</code><code>##

You are in 'C:\Documents and Settings\liverpole\perl' on the current drive
You are in 'D:\testdir' on the 'D' drive

 Volume in drive C has no label.
 Volume Serial Number is E451-D99E

 Directory of C:\Documents and Settings\liverpole\perl

[.]     [..]    dirtest.pl    dirtest.pl~
               2 File(s)            836 bytes
               2 Dir(s)  10,946,477,056 bytes free
 Volume in drive D is WIN2000
 Volume Serial Number is EEE2-EEE2

 Directory of D:\testdir

[.]     [..]    a.txt   b.txt   c.txt
               3 File(s)             24 bytes
               2 Dir(s)   3,777,839,104 bytes free