JavaScript

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.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

JavaScript

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 CkSsh();

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();