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50 lines
2.1 KiB
Markdown
50 lines
2.1 KiB
Markdown
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write-file-atomic
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-----------------
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This is an extension for node's `fs.writeFile` that makes its operation
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atomic and allows you set ownership (uid/gid of the file).
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### var writeFileAtomic = require('write-file-atomic')<br>writeFileAtomic(filename, data, [options], callback)
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* filename **String**
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* data **String** | **Buffer**
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* options **Object**
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* chown **Object**
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* uid **Number**
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* gid **Number**
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* encoding **String** | **Null** default = 'utf8'
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* fsync **Boolean** default = true
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* mode **Number** default = 438 (aka 0666 in Octal)
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* Promise **Object** default = native Promise object
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callback **Function**
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Atomically and asynchronously writes data to a file, replacing the file if it already
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exists. data can be a string or a buffer.
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The file is initially named `filename + "." + murmurhex(__filename, process.pid, ++invocations)`.
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If writeFile completes successfully then, if passed the **chown** option it will change
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the ownership of the file. Finally it renames the file back to the filename you specified. If
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it encounters errors at any of these steps it will attempt to unlink the temporary file and then
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pass the error back to the caller.
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If multiple writes are concurrently issued to the same file, the write operations are put into a queue and serialized in the order they were called, using Promises. Native promises are used by default, but you can inject your own promise-like object with the **Promise** option. Writes to different files are still executed in parallel.
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If provided, the **chown** option requires both **uid** and **gid** properties or else
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you'll get an error.
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The **encoding** option is ignored if **data** is a buffer. It defaults to 'utf8'.
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If the **fsync** option is **false**, writeFile will skip the final fsync call.
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Example:
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```javascript
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writeFileAtomic('message.txt', 'Hello Node', {chown:{uid:100,gid:50}}, function (err) {
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if (err) throw err;
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console.log('It\'s saved!');
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});
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```
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### var writeFileAtomicSync = require('write-file-atomic').sync<br>writeFileAtomicSync(filename, data, [options])
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The synchronous version of **writeFileAtomic**.
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