Unicode C++

SSH Exec (Execute Command Line)

Demonstrates running a single command on an SSH server with an exec request and retrieving its output. The example connects, authenticates, opens a session channel, sends the command, reads until the server closes the channel, and then checks the exit status.

Background: exec is the workhorse of SSH automation: it runs one command and the server closes the channel when the command exits, which is a definitive end-of-output signal. No PTY is involved, so the shell runs non-interactively — no prompt, no echoed input, no ANSI escape codes — giving clean, parseable output. Remember that an accepted exec request only means the request was accepted; the command's own success is reported through the channel exit status. Command syntax depends on the remote shell, which is the user's default shell on Linux/UNIX and usually CMD.EXE on Windows SSH servers.

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#include <CkSshW.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  Demonstrates running a single command on an SSH server with an exec request and retrieving
    //  its output.  An exec request runs one command and the server closes the channel when it
    //  finishes -- no PTY and no shell prompt are involved, so the output is clean and parseable.

    CkSshW ssh;

    //  The hostname may be a hostname or an IP address.
    const wchar_t *hostname = L"ssh.example.com";
    int port = 22;
    success = ssh.Connect(hostname,port);
    if (success == false) {
        wprintf(L"%s\n",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.
    const wchar_t *password = L"mySshPassword";

    success = ssh.AuthenticatePw(L"mySshLogin",password);
    if (success == false) {
        wprintf(L"%s\n",ssh.lastErrorText());
        return;
    }

    //  Open a session channel.  Several session channels may be open at once on one connection.
    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        wprintf(L"%s\n",ssh.lastErrorText());
        return;
    }

    //  The command syntax depends on the remote system's shell.  On Linux/UNIX it is typically the
    //  user's default shell; on Windows SSH servers it is usually CMD.EXE.
    //    Linux/UNIX:  "ls -l /tmp"        or  "cd /etc; ls -la"
    //    Windows:     "dir"               or  "\"cd \\temp&&dir\""
    success = ssh.SendReqExec(channelNum,L"ls -l /tmp");
    if (success == false) {
        wprintf(L"%s\n",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);

    //  Read the output until the server sends channel close, which happens when the command exits.
    success = ssh.ChannelReceiveToClose(channelNum);
    if (success == false) {
        wprintf(L"%s\n",ssh.lastErrorText());
        return;
    }

    const wchar_t *cmdOutput = ssh.getReceivedText(channelNum,L"utf-8");
    if (ssh.get_LastMethodSuccess() == false) {
        wprintf(L"%s\n",ssh.lastErrorText());
        return;
    }

    wprintf(L"%s\n",cmdOutput);

    //  An accepted exec request does not mean the command succeeded.  Check the exit status.
    if (ssh.ChannelReceivedExitStatus(channelNum)) {
        wprintf(L"Exit status: %d\n",ssh.GetChannelExitStatus(channelNum));
    }

    ssh.Disconnect();
    }