Node.js

Send EOF on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

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function chilkatExample() {

    var success = false;

    //  Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
    //  only argument is the channel number.  EOF closes only the client-to-server direction; output
    //  may still be received from the server.

    var ssh = new chilkat.Ssh();

    var sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        console.log(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.
    var password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        console.log(ssh.LastErrorText);
        return;
    }

    var channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        console.log(ssh.LastErrorText);
        return;
    }

    success = ssh.SendReqExec(channelNum,"wc -l");
    if (success == false) {
        console.log(ssh.LastErrorText);
        return;
    }

    //  Send input to the remote command.
    success = ssh.ChannelSendString(channelNum,"line one\nline two\nline three\n","utf-8");
    if (success == false) {
        console.log(ssh.LastErrorText);
        return;
    }

    //  Signal that no more input will be sent.  Do not send more data on this channel afterward.
    success = ssh.ChannelSendEof(channelNum);
    if (success == false) {
        console.log(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.ReadTimeoutMs = 15000;

    //  Output can still be received after EOF is sent.
    success = ssh.ChannelReceiveToClose(channelNum);
    if (success == false) {
        console.log(ssh.LastErrorText);
        return;
    }

    var output = ssh.GetReceivedText(channelNum,"utf-8");
    if (ssh.LastMethodSuccess == false) {
        console.log(ssh.LastErrorText);
        return;
    }

    console.log(output);

    ssh.Disconnect();

}

chilkatExample();