Perl

SSH Exec (Execute Command Line)

Demonstrates running a single command on an SSH server with an exec request and retrieving its output. The example connects, authenticates, opens a session channel, sends the command, reads until the server closes the channel, and then checks the exit status.

Background: exec is the workhorse of SSH automation: it runs one command and the server closes the channel when the command exits, which is a definitive end-of-output signal. No PTY is involved, so the shell runs non-interactively — no prompt, no echoed input, no ANSI escape codes — giving clean, parseable output. Remember that an accepted exec request only means the request was accepted; the command's own success is reported through the channel exit status. Command syntax depends on the remote shell, which is the user's default shell on Linux/UNIX and usually CMD.EXE on Windows SSH servers.

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Perl

use chilkat();

$success = 0;

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  Demonstrates running a single command on an SSH server with an exec request and retrieving
#  its output.  An exec request runs one command and the server closes the channel when it
#  finishes -- no PTY and no shell prompt are involved, so the output is clean and parseable.

$ssh = chilkat::CkSsh->new();

#  The hostname may be a hostname or an IP address.
$hostname = "ssh.example.com";
$port = 22;
$success = $ssh->Connect($hostname,$port);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\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.
$password = "mySshPassword";

$success = $ssh->AuthenticatePw("mySshLogin",$password);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  Open a session channel.  Several session channels may be open at once on one connection.
$channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  The command syntax depends on the remote system's shell.  On Linux/UNIX it is typically the
#  user's default shell; on Windows SSH servers it is usually CMD.EXE.
#    Linux/UNIX:  "ls -l /tmp"        or  "cd /etc; ls -la"
#    Windows:     "dir"               or  "\"cd \\temp&&dir\""
$success = $ssh->SendReqExec($channelNum,"ls -l /tmp");
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\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->put_ReadTimeoutMs(15000);

#  Read the output until the server sends channel close, which happens when the command exits.
$success = $ssh->ChannelReceiveToClose($channelNum);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

$cmdOutput = $ssh->getReceivedText($channelNum,"utf-8");
if ($ssh->get_LastMethodSuccess() == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

print $cmdOutput . "\r\n";

#  An accepted exec request does not mean the command succeeded.  Check the exit status.
if ($ssh->ChannelReceivedExitStatus($channelNum)) {
    print "Exit status: " . $ssh->GetChannelExitStatus($channelNum) . "\r\n";
}

$ssh->Disconnect();