README.md

write-file-atomic

Forked from https://github.com/npm/write-file-atomic to include npm#25, for use with AVA.

---

This is an extension for node's fs.writeFile that makes its operation atomic and allows you set ownership (uid/gid of the file).

var writeFileAtomic = require('write-file-atomic')
writeFileAtomic(filename, data, [options], callback)

• filename String
• data String | Buffer
• options Object
  • chown Object
    • uid Number
    • gid Number
  • encoding String | Null default = 'utf8'
  • fsync Boolean default = true
  • mode Number default = 438 (aka 0666 in Octal) callback Function

Atomically and asynchronously writes data to a file, replacing the file if it already exists. data can be a string or a buffer.

The file is initially named filename + "." + murmurhex(__filename, process.pid, ++invocations). If writeFile completes successfully then, if passed the chown option it will change the ownership of the file. Finally it renames the file back to the filename you specified. If it encounters errors at any of these steps it will attempt to unlink the temporary file and then pass the error back to the caller.

If provided, the chown option requires both uid and gid properties or else you'll get an error.

The encoding option is ignored if data is a buffer. It defaults to 'utf8'.

If the fsync option is false, writeFile will skip the final fsync call.

The callback is always invoked with the initial (temporary) filename.

Example:

writeFileAtomic('message.txt', 'Hello Node', {chown:{uid:100,gid:50}}, function (err) {
  if (err) throw err;
  console.log('It\'s saved!');
});

var writeFileAtomicSync = require('write-file-atomic').sync
writeFileAtomicSync(filename, data, [options])

The synchronous version of writeFileAtomic. Returns the initial (temporary) filename.