### Perl Script: How to find if variable is defined or not?

Below is a simple perl script which explains how to find if any given variable is defined or not.

Feel free to copy and use this code.

Source
: cat undefined.pl
#!/usr/bin/perl

use strict;
use warnings;

my \$Undefined;
my \$Defined = "linuxpoison";

print "The value of Undefined is ", defined \$Undefined, "\n";
print "The value of Defined is ", defined \$Defined, "\n";

print "------------------------------\n";

\$Undefined = \$Defined;
\$Defined = undef;

print "The value of Undefined is ", defined \$Undefined, "\n";
print "The value of Defined is ", defined \$Defined, "\n";

Output: perl undefined.pl
The value of Undefined is
The value of Defined is 1
------------------------------
The value of Undefined is 1
The value of Defined is