#!/usr/local/bin/perl

use strict;
use warnings;

my $file = '/root/Desktop/';
sleep 5;
$file =  system("import -window root MyScreenshot.png");
print $file, "\n";
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Ouch! That really hurts my eyes!

• Why do you sleep before taking a screenshot?
• Why do you assign a useless constant to $file?
• Are you sure system() returns a file or a filename? Hint: It doesn't!
• So why do you assign the return value to a variable named $file?
• Why do you mess with the notoriously problematic default shell instead of using the multiple-argument form of system?
• Why do you print the return value of system to STDOUT?

At least, you use strict and warnings.

use strict;
use warnings;

system("import -window root MyScreenshot.png");
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Better, but still problematic: You still invoke the default shell, begging for trouble. All error checks are missing. Yes, system() may fail. For example, because there is no import utility -- e.g. when ImageMagick is not installed. Or because there is some other tool named import, with completely different parameters a and a completely different purpose.

Alexander