use of uninitialized value. How can I fix this error? - perl

Question

#!/usr/bin/perl
use Net::SSH::Expect;
use warnings;
use strict;
#my($stdout, $stderr, $exit) = $ssh->cmd("ls -l /home/$usr")
# Making an ssh connection with user-password authentication
# 1) construct the object
my $ssh = Net::SSH::Expect->new (
host => "host",
password=> 'pwd',
user => 'user',
raw_pty => 1
#Expect=>log_file("finally.txt")
);
# 2) logon to the SSH server using those credentials.
# test the login output to make sure we had success
my $login_output = $ssh->login();
if ($login_output !~ /Welcome/) {
die "Login has failed. Login output was $login_output";
}
# disable terminal translations and echo on the SSH server
# executing on the server the stty command:
$ssh->exec("stty raw -echo");
my $stdout = $ssh->send(chr(13));
my $stdout2 = $ssh->send("SDT-FI");
my $stdout3 = $ssh->send("ENG");
my $stdout4 = $ssh->send('SORT FI-WIP "84144"');
my $stdout5 = $ssh->send(chr(13));
my $stdout6 = $ssh->send("OFF");
my $stdout7 = $ssh->send(chr(13));
print($stdout3);
#$expect->log_file("adp-n.txt");
#y $line;
# returns the next line, removing it from the input stream:
# while ( defined ($line = $ssh->read_all()) ) {
# print $line . "\n";
#}
So i am trying to print $stdout3 so i can get information about the output
but i keep getting " use of uninitialized value $stdout3 in print at connnn3.pl line 50"
is there something in my code wrong?
how can i fix this?
UPDATE, SOLVED!
The reason why it was returning "use of uninitialized value" was because the function
send()
Is void, so instead i used
exec()
And that solved it

Answer 1

From the documentation of Net::SSH::Expect:
void send($string) - sends $string to the SSH server, returns nothing
Thus, send obviously returns nothing (void) and that's why you get this warning when trying to print the (non-existing) return value of send. If you want to get data back from the server use peek, eat, read_all or similar as documented.