This demonstrates the use of the conditional and print to handle the undefined value without warning. 
 
#!/usr/bin/perl
use strict;
use warnings;
use strict 'vars';
use Getopt::Std;

#Setting options
# u:username
# h:hostname
# p:password
# k:SSH Key

our ($opt_u, $opt_h, $opt_p, $opt_k);

getopts("u:h:p:k:");

#### TEST SECTION ###
print "\$opt_u=";
print $opt_u ? $opt_u : "Undefined" ;
print "\n";

print "\$opt_h=";
print $opt_h ? $opt_h : "Undefined" ;
print "\n";

print "\$opt_p=";
print $opt_p ? $opt_p : "Undefined" ;
print "\n";

print "\$opt_k=";
print $opt_k ? $opt_k : "Undefined" ;
print "\n";


$ ./test.pl 
$opt_u=Undefined
$opt_h=Undefined
$opt_p=Undefined
$opt_k=Undefined

$ ./test.pl  -u abc -h def -p ghi -k jkl                              
+   
$opt_u=abc
$opt_h=def
$opt_p=ghi
$opt_k=jkl

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In reply to Re: Use of uninitialized value in print by mikelieman
in thread Use of uninitialized value in print by Psyber Netik

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