Dart

Receive an SSH Channel Until Close

Demonstrates the Chilkat Ssh.ChannelReceiveToClose method, which receives data on a channel until the server sends and Chilkat processes channel CLOSE. The only argument is the channel number. EOF alone does not complete this method.

Important: Set the ReadTimeoutMs property before calling this method. It defaults to 0, meaning no limit, so without it the call waits forever if the server never sends channel close.

Background: This is the simplest and most reliable way to collect the complete output of a one-shot exec command, because the server closes the channel when the command finishes. It is not appropriate for an interactive shell, which never closes on its own — use the poll-based methods there instead. Both stdout and stderr are processed, merged or kept separate according to StderrToStdout.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the Ssh.ChannelReceiveToClose method, which receives data on a channel until the
  // server sends channel CLOSE.  The only argument is the channel number.  EOF alone does not
  // complete this method.

  final ssh = CkSsh();

  final sshPort = 22;
  try {
    ssh.connect('ssh.example.com', sshPort);
  } on ChilkatException catch (e) {
    print(e.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.
  final password = 'mySshPassword';

  try {
    ssh.authenticatePw('mySshLogin', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final channelNum = ssh.openSessionChannel();
  if (channelNum < 0) {
    print(ssh.lastErrorText);
    return;
  }

  try {
    ssh.sendReqExec(channelNum, 'ls -l /tmp');
  } on ChilkatException catch (e) {
    print(e.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;

  // Receive everything the command produces, up to and including channel close.
  try {
    ssh.channelReceiveToClose(channelNum);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final String output;
  try {
    output = ssh.getReceivedText(channelNum, 'utf-8');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print(output);

  ssh.disconnect();
}