SSH ChannelReceiveUntilMatchN (Match Any of Several Prompts)

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Demonstrates ChannelReceiveUntilMatchN, which receives until any one of several patterns is matched. This is useful when driving an interactive session where the shell prompt differs from device to device.

Note: This example deliberately requests a PTY. Matching a shell prompt only works in an interactive session — without a PTY the shell runs non-interactively and never prints a prompt at all. For scripted use, omit the PTY and match on a marker your own command echoes.

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

async function chilkatExample() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // Demonstrates ChannelReceiveUntilMatchN, which receives until ANY one of several patterns is
  // matched.  This is useful when driving an interactive session where the shell prompt varies
  // from device to device.
  // 
  // Note: This example deliberately DOES request a PTY.  Matching a shell prompt only works in an
  // interactive session -- without a PTY the shell runs non-interactively and never prints a
  // prompt at all.  For scripted use where no prompt is needed, omit the PTY and match on a
  // marker your own command echoes instead.

  const ssh = new Ssh();

  // The remote shell prompt may be any of these, depending on the device.
  const saPrompts = new StringArray();
  saPrompts.append('~$');
  saPrompts.append('mars#');
  saPrompts.append('jupiter%');
  saPrompts.append('chilkat$');
  saPrompts.append('admin>');

  const hostname = 'ssh.example.com';
  const port = 22;
  try {
    await ssh.connectAsync(hostname, port);
  } 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;
  }

  // Request a pseudo-terminal so the shell runs interactively and prints prompts.  A "dumb"
  // terminal is used so that ANSI escape sequences are not mixed into the output.
  const termType = 'dumb';
  const widthInChars = 120;
  const heightInChars = 40;
  const pixWidth = 0;
  const pixHeight = 0;
  try {
    await ssh.sendReqPtyAsync(channelNum, termType, widthInChars, heightInChars, pixWidth, pixHeight);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  try {
    await ssh.sendReqShellAsync(channelNum);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  // IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
  // which means no limit -- without it, this call waits forever if the received data never
  // contains a match.
  ssh.readTimeoutMs = 15000;

  const caseSensitive = true;

  // Read the initial login text up to the first prompt.
  try {
    await ssh.channelReceiveUntilMatchNAsync(channelNum, saPrompts, 'utf-8', caseSensitive);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

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

  console.log(cmdOutput);

  // ---- 1st command ----
  try {
    await ssh.channelSendStringAsync(channelNum, 'cd /tmp\n', 'utf-8');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  try {
    await ssh.channelReceiveUntilMatchNAsync(channelNum, saPrompts, 'utf-8', caseSensitive);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  // Retrieving the text also clears the receive buffer, which matters: if a prompt were left
  // buffered, the next receive would match it immediately and return the wrong output.
  try {
    cmdOutput = ssh.getReceivedText(channelNum, 'utf-8');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  console.log(cmdOutput);

  // ---- 2nd command ----
  try {
    await ssh.channelSendStringAsync(channelNum, 'ls\n', 'utf-8');
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  try {
    await ssh.channelReceiveUntilMatchNAsync(channelNum, saPrompts, 'utf-8', caseSensitive);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

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

  console.log(cmdOutput);

  // Finish the session.
  try {
    await ssh.channelSendEofAsync(channelNum);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

  try {
    await ssh.channelReceiveToCloseAsync(channelNum);
  } catch {
    console.log(ssh.lastErrorText);
    return;
  }

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

  console.log(cmdOutput);

  ssh.disconnect();
}