C++

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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#include <CkSsh.h>

void ChilkatSample(void)
    {
    bool 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.

    CkSsh ssh;

    int sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        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.
    const char *password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    success = ssh.SendReqExec(channelNum,"grep -q root /etc/passwd");
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        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) {
        std::cout << ssh.lastErrorText() << "\r\n";
        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)) {
        int exitStatus = ssh.GetChannelExitStatus(channelNum);
        std::cout << "Exit status: " << exitStatus << "\r\n";

        //  By convention, 0 means the remote command succeeded.
        if (exitStatus == 0) {
            std::cout << "The remote command succeeded." << "\r\n";
        }
        else {
            std::cout << "The remote command reported a failure." << "\r\n";
        }

    }

    ssh.Disconnect();
    }