226 lines
4.8 KiB
Markdown
226 lines
4.8 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Write File
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> Write data to a file.
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<section class="usage">
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## Usage
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```javascript
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var writeFile = require( '@stdlib/fs/write-file' );
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```
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#### writeFile( file, data\[, options], clbk )
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Asynchronously write `data` to a `file`.
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```javascript
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var join = require( 'path' ).join;
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var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );
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writeFile( fpath, 'beep boop\n', onWrite );
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function onWrite( error ) {
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if ( error ) {
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throw error;
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}
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}
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```
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The `data` argument may be either a `string` or a [`Buffer`][@stdlib/buffer/ctor].
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```javascript
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var join = require( 'path' ).join;
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var string2buffer = require( '@stdlib/buffer/from-string' );
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var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );
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writeFile( fpath, string2buffer( 'beep boop\n' ), onWrite );
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function onWrite( error ) {
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if ( error ) {
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throw error;
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}
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}
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```
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The function accepts the same `options` and has the same defaults as [`fs.writeFile()`][node-fs].
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#### writeFile.sync( file, data\[, options] )
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Synchronously writes `data` to a `file`.
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```javascript
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var join = require( 'path' ).join;
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var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );
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var err = writeFile.sync( fpath, 'beep boop\n' );
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if ( err instanceof Error ) {
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throw err;
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}
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```
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The function accepts the same `options` and has the same defaults as [`fs.writeFileSync()`][node-fs].
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- The difference between this `writeFile.sync` and [`fs.writeFileSync()`][node-fs] is that [`fs.writeFileSync()`][node-fs] will throw if an `error` is encountered (e.g., if given a non-existent directory path) and this API will return an `error`. Hence, the following anti-pattern
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<!-- run-disable -->
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```javascript
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var fs = require( 'fs' );
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// Check for directory path existence to prevent an error being thrown...
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if ( fs.existsSync( '/path/to' ) ) {
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fs.writeFileSync( '/path/to/file.txt', 'beep boop\n' );
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}
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```
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can be replaced by an approach which addresses existence via `error` handling.
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<!-- run-disable -->
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```javascript
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var writeFile = require( '@stdlib/fs/write-file' );
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// Explicitly handle the error...
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var err = writeFile.sync( '/path/to/file.txt', 'beep boop\n' );
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if ( err instanceof Error ) {
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// You choose what to do...
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throw err;
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}
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```
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var join = require( 'path' ).join;
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var writeFile = require( '@stdlib/fs/write-file' );
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var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );
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// Synchronously write data to a file:
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var err = writeFile.sync( fpath, 'beep boop\n', 'utf8' );
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// returns null
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console.log( err instanceof Error );
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// => false
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// Asynchronously write data to a file:
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writeFile( fpath, 'beep boop\n', onWrite );
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function onWrite( error ) {
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if ( error ) {
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console.error( 'Error: %s', error.message );
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}
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console.log( 'Success!' );
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}
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```
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</section>
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<!-- /.examples -->
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* * *
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<section class="cli">
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## CLI
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<section class="usage">
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### Usage
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```text
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Usage: write-file [options] <filepath>
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Options:
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-h, --help Print this message.
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-V, --version Print the package version.
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--enc, --encoding encoding Encoding. Default: 'utf8'.
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--flag flag Flag. Default: 'r'.
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--mode mode Mode. Default: 0o666.
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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### Notes
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- Relative output file paths are resolved relative to the current working directory.
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- Errors are written to `stderr`.
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- File contents should be provided over `stdin` as part of a [standard stream][standard-stream] pipeline.
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</section>
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<!-- /.notes -->
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<section class="examples">
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### Examples
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```bash
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$ printf 'beep boop\n' | write-file ./examples/fixtures/file.txt
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.cli -->
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<section class="links">
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[node-fs]: https://nodejs.org/api/fs.html
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[@stdlib/buffer/ctor]: https://www.npmjs.com/package/@stdlib/buffer-ctor
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[standard-stream]: http://en.wikipedia.org/wiki/Pipeline_%28Unix%29
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</section>
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<!-- /.links -->
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