Unicode 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 <C_CkSshW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSshW ssh;
    int sshPort;
    const wchar_t *password;
    int channelNum;
    int exitStatus;

    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.

    ssh = CkSshW_Create();

    sshPort = 22;
    success = CkSshW_Connect(ssh,L"ssh.example.com",sshPort);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        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.
    password = L"mySshPassword";

    success = CkSshW_AuthenticatePw(ssh,L"mySshLogin",password);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    channelNum = CkSshW_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    success = CkSshW_SendReqExec(ssh,channelNum,L"grep -q root /etc/passwd");
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        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.
    CkSshW_putReadTimeoutMs(ssh,15000);

    success = CkSshW_ChannelReceiveToClose(ssh,channelNum);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    //  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
    //  channel, because the completed channel record can be discarded.
    if (CkSshW_ChannelReceivedExitStatus(ssh,channelNum)) {
        exitStatus = CkSshW_GetChannelExitStatus(ssh,channelNum);
        wprintf(L"Exit status: %d\n",exitStatus);

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

    }

    CkSshW_Disconnect(ssh);


    CkSshW_Dispose(ssh);

    }