React Native

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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React Native

import { Ssh } from '@chilkat/react-native'

async function chilkatExample() {
  // 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.

  const ssh = new Ssh();

  const sshPort = 22;
  try {
    await ssh.connectAsync('ssh.example.com', sshPort);
  } catch {
    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.
  const password = 'mySshPassword';

  try {
    await ssh.authenticatePwAsync('mySshLogin', password);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  const channelNum = await ssh.openSessionChannelAsync();
  if (channelNum < 0) {
    console.log(ssh.lastErrorText);
    return;
  }

  try {
    await ssh.sendReqExecAsync(channelNum, 'wc -l');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  // Send input to the remote command.
  try {
    await ssh.channelSendStringAsync(channelNum, 'line one\nline two\nline three\n', 'utf-8');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  // Signal that no more input will be sent.  Do not send more data on this channel afterward.
  try {
    await ssh.channelSendEofAsync(channelNum);
  } catch {
    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.
  try {
    await ssh.channelReceiveToCloseAsync(channelNum);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  let output: string;
  try {
    output = ssh.getReceivedText(channelNum, 'utf-8');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  console.log(output);

  ssh.disconnect();
}