JavaScript

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.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

JavaScript

var success = false;

//  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 true.

var ssh = new CkSsh();

var sshPort = 22;
success = ssh.Connect("ssh.example.com",sshPort);
if (success == false) {
    console.log(ssh.LastErrorText);
    return;
}

//  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.
var password = "mySshPassword";

success = ssh.AuthenticatePw("mySshLogin",password);
if (success == false) {
    console.log(ssh.LastErrorText);
    return;
}

var channelNum = ssh.OpenSessionChannel();
if (channelNum < 0) {
    console.log(ssh.LastErrorText);
    return;
}

success = ssh.SendReqExec(channelNum,"grep -q root /etc/passwd");
if (success == false) {
    console.log(ssh.LastErrorText);
    return;
}

//  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 == false) {
    console.log(ssh.LastErrorText);
    return;
}

//  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)) {
    var exitStatus = ssh.GetChannelExitStatus(channelNum);
    console.log("Exit status: " + exitStatus);

    //  By convention, 0 means the remote command succeeded.
    if (exitStatus == 0) {
        console.log("The remote command succeeded.");
    }
    else {
        console.log("The remote command reported a failure.");
    }

}

ssh.Disconnect();