React Native

Wait for a Message on Any SSH Channel

Demonstrates the Chilkat Ssh.WaitForChannelMessage method, which waits for the next SSH channel message on any channel. The only argument is the poll timeout: 0 for a nonblocking check, a positive value to wait that long, or a negative value to wait with no method-level timeout. It returns the channel number the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error such as a lost connection.

Background: When several channels are active at once, waiting on one specific channel would block while others sit ready. This method is the multiplexed alternative — it returns as soon as any channel has activity and tells you which one, so a single loop can service them all. The explicit timeout argument governs the wait; shorter ReadTimeoutMs values do not cut it short.

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React Native

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

async function chilkatExample() {
  // Demonstrates the Ssh.WaitForChannelMessage method, which waits for the next SSH channel
  // message on ANY channel.  The only argument is the poll timeout in milliseconds: 0 for a
  // nonblocking check, a positive value to wait that long, or a negative value to wait with no
  // method-level timeout.

  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, 'ls -l /tmp');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  // Wait up to 5 seconds for the next channel message.  The return value is the channel number
  // the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error.
  const pollTimeoutMs = 5000;
  const result = await ssh.waitForChannelMessageAsync(pollTimeoutMs);

  if (result === -2) {
    console.log(ssh.lastErrorText);
    return;
  }

  if (result === -1) {
    console.log('No channel message arrived before the timeout.');
  }

  if (result >= 0) {
    console.log(`Processed a message for channel ${result}`);
  }

  ssh.disconnect();
}