Perl

Get the Exit Status of a Remote SSH Command

Demonstrates the Chilkat Ssh.GetChannelExitStatus method, which returns the remote process exit status for a channel. The only argument is the channel number. Call it only after ChannelReceivedExitStatus returns true.

Background: The exit status is how you learn whether a remote command actually succeeded — recall that a successful exec request only means the request was accepted. By Unix convention 0 means success and any nonzero value indicates a failure. Retrieve it promptly after the receive operation and before calling unrelated SSH methods or releasing the channel, since the completed channel record can be discarded.

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use strict;
use warnings;
use Chilkat2;

# Demonstrates the Ssh.GetChannelExitStatus method, which returns the remote process exit
# status for a channel.  The only argument is the channel number.  Call it only after
# ChannelReceivedExitStatus returns 1.

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;
}

my $channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->LastErrorText, "\n";
    exit;
}

$success = $ssh->SendReqExec($channelNum, 'grep -q root /etc/passwd');
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);

$success = $ssh->ChannelReceiveToClose($channelNum);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
# channel, because the completed channel record can be discarded.
if ($ssh->ChannelReceivedExitStatus($channelNum)) {
    my $exitStatus = $ssh->GetChannelExitStatus($channelNum);
    print 'Exit status: ', $exitStatus, "\n";

    # By convention, 0 means the remote command succeeded.
    if ($exitStatus == 0) {
        print "The remote command succeeded.\n";
    } else {
        print "The remote command reported a failure.\n";
    }
}

$ssh->Disconnect();