Perl

Run a Command on an SSH Session Channel

Demonstrates the Chilkat Ssh.SendReqExec method, which requests execution of a command on a session channel. The first argument is the channel number and the second is the command line. This example runs a command, reads the output until the channel closes, and prints it.

Background: exec is the workhorse for automation: run one command, collect its output, and finish — no interactive shell needed. Note carefully that a true return means the request was accepted, not that the command succeeded. To learn the command's outcome, read its output and check the channel exit status.

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use strict;
use warnings;
use Chilkat2;

# Demonstrates the Ssh.SendReqExec method, which requests execution of a command on a session
# channel.  The 1st argument is the channel number and the 2nd is the command line.

my $ssh = Chilkat2::Ssh->new;

my $sshPort = 22;
my $success = $ssh->Connect('ssh.example.com', $sshPort);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Normally you would not hard-code the password in source.  You should instead obtain it
# from an interactive prompt, environment variable, or a secrets vault.
my $password = 'mySshPassword';

$success = $ssh->AuthenticatePw('mySshLogin', $password);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Open a session channel.  A negative return value indicates failure.
my $channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Request execution of a command.  A 1 return means the server accepted the request; it
# does not mean the command itself succeeded.
$success = $ssh->SendReqExec($channelNum, 'ls -l /tmp');
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
# it, this call waits forever if the server never sends channel close.
$ssh->ReadTimeoutMs(15000);

# Read the command output until the server closes the channel.
$success = $ssh->ChannelReceiveToClose($channelNum);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

my $output = $ssh->GetReceivedText($channelNum, 'utf-8');
if (!$ssh->LastMethodSuccess) {
    print $ssh->LastErrorText, "\n";
    exit;
}

print $output, "\n";

$ssh->Disconnect();