(Swift 3,4,5...) Multiple SendReqExec on Same Connection

Shows how to execute a series of commands on an SSH server and retrieve each command's output (using SendReqExec). Each call to SendReqExec requires its own logical channel. This is not a separate SSH connection -- it's simply a new session channel on the existing SSH connection.

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func chilkatTest() {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let ssh = CkoSsh()!

    // Hostname may be an IP address or domain:
    var hostname: String? = "172.16.16.46"
    var port: Int = 22

    var success: Bool = ssh.connect(hostname, port: port)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // If receiving output from a command stalls for more than 5 seconds, then stop waiting.
    ssh.idleTimeoutMs = 5000

    // Authenticate using login/password:
    success = ssh.authenticatePw("myLogin", password: "myPassword")
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Open a session channel.  (It is possible to have multiple
    // session channels open simultaneously.)
    var channelNum: Int = ssh.openSessionChannel().intValue
    if channelNum < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Request a directory listing on the remote server:
    // If your server is Linux/UNIX, change the string from "dir" to "ls"
    // Note: Some SSH servers require a CRLF instead of a bare-LF
    var cmd: String? = "ls -al\n"
    success = ssh.sendReqExec(channelNum, command: cmd)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Read whatever output may already be available on the
    // SSH connection.  ChannelReadAndPoll returns the number of bytes
    // that are available in the channel's internal buffer that
    // are ready to be "picked up" by calling GetReceivedText
    // or GetReceivedData.
    // A return value of -1 indicates failure.
    // A return value of -2 indicates a failure via timeout.

    // The ChannelReadAndPoll method waits
    // for data to arrive on the connection usingi the IdleTimeoutMs
    // property setting.  Once the first data arrives, it continues
    // reading but instead uses the pollTimeoutMs passed in the 2nd argument:
    // A return value of -2 indicates a timeout where no data is received.
    var pollTimeoutMs: Int = 2000
    var n: Int = ssh.channelReadAndPoll(channelNum, pollTimeoutMs: pollTimeoutMs).intValue
    if n < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Close the channel:
    success = ssh.channelSendClose(channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Perhaps we did not receive all of the commands output.
    // To make sure,  call ChannelReceiveToClose to accumulate any remaining
    // output until the server's corresponding "channel close" is received.
    success = ssh.channelReceive(toClose: channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Get the accumulated output of the command:
    var cmdOutput: String?
    cmdOutput = ssh.getReceivedText(channelNum, charset: "ansi")
    if ssh.lastMethodSuccess == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    // Display the remote shell's command output:
    print("\(cmdOutput!)")
    print("----")

    // -----------------------------------------------------------------
    // Now for the 2nd SendReqExe (on the same connection,
    // but on a separate logical channel).
    // -----------------------------------------------------------------

    channelNum = ssh.openSessionChannel().intValue
    if channelNum < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    cmd = "nslookup chilkatsoft.com\n"
    success = ssh.sendReqExec(channelNum, command: cmd)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    pollTimeoutMs = 2000
    n = ssh.channelReadAndPoll(channelNum, pollTimeoutMs: pollTimeoutMs).intValue
    if n < 0 {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.channelSendClose(channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    success = ssh.channelReceive(toClose: channelNum)
    if success == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    cmdOutput = ssh.getReceivedText(channelNum, charset: "ansi")
    if ssh.lastMethodSuccess == false {
        print("\(ssh.lastErrorText!)")
        return
    }

    print("\(cmdOutput!)")

}