Write Text at a 32-bit Offset in a Remote SFTP File

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Demonstrates the Chilkat SFtp.WriteFileText32 method, which encodes text and writes it at a specific 32-bit byte offset in an open handle. The arguments are the handle, the offset, the charset, and the text.

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

async function chilkatExample() {
  // Demonstrates the SFtp.WriteFileText32 method, which encodes text and writes it at a specific
  // 32-bit byte offset in an open handle.  The 1st argument is the handle, the 2nd is the offset,
  // the 3rd is the charset, and the 4th is the text.

  const sftp = new SFtp();

  // Connect, authenticate, and initialize the SFTP subsystem.
  const port = 22;
  try {
    await sftp.connectAsync('sftp.example.com', port);
  } catch {
    console.log(sftp.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 sftp.authenticatePwAsync('mySshLogin', password);
  } catch {
    console.log(sftp.lastErrorText);
    return;
  }

  try {
    await sftp.initializeSftpAsync();
  } catch {
    console.log(sftp.lastErrorText);
    return;
  }

  // Open the remote file for read/write so an existing file can be modified in place.
  let handle: string;
  try {
    handle = await sftp.openFileAsync('subdir/record.dat', 'readWrite', 'openOrCreate');
  } catch {
    console.log(sftp.lastErrorText);
    return;
  }

  // Overwrite 5 bytes starting at offset 10.  The offset is a byte position, not a character
  // position, so it must account for the encoded size of any multibyte characters.
  const offset = 10;
  try {
    await sftp.writeFileText32Async(handle, offset, 'utf-8', 'HELLO');
  } catch {
    console.log(sftp.lastErrorText);
    return;
  }

  try {
    await sftp.closeHandleAsync(handle);
  } catch {
    console.log(sftp.lastErrorText);
    return;
  }

  console.log('Wrote at the specified offset.');

  sftp.disconnect();
}