Java

Check Whether an SSH Exit Status Was Received

Demonstrates the Chilkat Ssh.ChannelReceivedExitStatus method, which reports whether the server supplied an exit-status value for a channel. The only argument is the channel number. When it returns true, call GetChannelExitStatus to read the value.

Background: Always test this before reading the exit status, because the server is not required to send one for every channel type or command — treating a missing status as "0" would silently turn a failure into a success. Exit status is independent of EOF and CLOSE: it can arrive after EOF and either before or together with CLOSE.

Chilkat Java Downloads

Download Chilkat for Java

Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    //  Demonstrates the Ssh.ChannelReceivedExitStatus method, which reports whether the server
    //  supplied an exit-status value for a channel.  The only argument is the channel number.  When
    //  it returns true, call GetChannelExitStatus to read the value.

    CkSsh ssh = new CkSsh();

    int sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        System.out.println(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.
    String password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        System.out.println(ssh.lastErrorText());
        return;
        }

    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        System.out.println(ssh.lastErrorText());
        return;
        }

    success = ssh.SendReqExec(channelNum,"test -f /etc/hosts");
    if (success == false) {
        System.out.println(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.put_ReadTimeoutMs(15000);

    success = ssh.ChannelReceiveToClose(channelNum);
    if (success == false) {
        System.out.println(ssh.lastErrorText());
        return;
        }

    //  The server is not required to send an exit status for every channel type or command.
    if (ssh.ChannelReceivedExitStatus(channelNum)) {
        int exitStatus = ssh.GetChannelExitStatus(channelNum);
        System.out.println("Exit status: " + exitStatus);
        }
    else {
        System.out.println("The server did not provide an exit status.");
        }

    ssh.Disconnect();
  }
}