SSH Exec (Execute Command Line)

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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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    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.

    ssh := chilkat.NewSsh()

    //  The hostname may be a hostname or an IP address.
    hostname := "ssh.example.com"
    port := 22
    success = ssh.Connect(hostname,port)
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        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 := "mySshPassword"

    success = ssh.AuthenticatePw("mySshLogin",password)
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    //  Open a session channel.  Several session channels may be open at once on one connection.
    channelNum := ssh.OpenSessionChannel()
    if channelNum < 0 {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        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,"ls -l /tmp")
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        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.SetReadTimeoutMs(15000)

    //  Read the output until the server sends channel close, which happens when the command exits.
    success = ssh.ChannelReceiveToClose(channelNum)
    if success == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    cmdOutput := ssh.GetReceivedText(channelNum,"utf-8")
    if ssh.LastMethodSuccess() == false {
        fmt.Println(ssh.LastErrorText())
        ssh.DisposeSsh()
        return
    }

    fmt.Println(*cmdOutput)

    //  An accepted exec request does not mean the command succeeded.  Check the exit status.
    if ssh.ChannelReceivedExitStatus(channelNum) {
        fmt.Println("Exit status: ", ssh.GetChannelExitStatus(channelNum))
    }

    ssh.Disconnect()

    ssh.DisposeSsh()