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.

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import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Ssh;

public class ChilkatExample {

    public static void main(String[] args) {
        // 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.

        Ssh ssh = new Ssh();

        int sshPort = 22;
        try {
            ssh.connect("ssh.example.com", sshPort);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            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";

        try {
            ssh.authenticatePw("mySshLogin", password);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

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

        try {
            ssh.sendReqExec(channelNum, "test -f /etc/hosts");

            // 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.setReadTimeoutMs(15000);

            ssh.channelReceiveToClose(channelNum);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            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();
    }
}