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Write File

Write data to a file.

Installation

npm install @stdlib/fs-write-file

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).
• To use as a general utility for the command line, install the corresponding CLI package globally.

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var writeFile = require( '@stdlib/fs-write-file' );

writeFile( file, data[, options], clbk )

Asynchronously writes data to a file.

var join = require( 'path' ).join;

var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );

writeFile( fpath, 'beep boop\n', onWrite );

function onWrite( error ) {
    if ( error ) {
        throw error;
    }
}

The data argument may be either a string or a Buffer.

var join = require( 'path' ).join;
var string2buffer = require( '@stdlib/buffer-from-string' );

var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );

writeFile( fpath, string2buffer( 'beep boop\n' ), onWrite );

function onWrite( error ) {
    if ( error ) {
        throw error;
    }
}

The function accepts the same options and has the same defaults as fs.writeFile().

writeFile.sync( file, data[, options] )

Synchronously writes data to a file.

var join = require( 'path' ).join;

var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );

var err = writeFile.sync( fpath, 'beep boop\n' );
if ( err instanceof Error ) {
    throw err;
}

The function accepts the same options and has the same defaults as fs.writeFileSync().

Notes

• The difference between this writeFile.sync and fs.writeFileSync() is that fs.writeFileSync() 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

  var fs = require( 'fs' );
  
  // Check for directory path existence to prevent an error being thrown...
  if ( fs.existsSync( '/path/to' ) ) {
      fs.writeFileSync( '/path/to/file.txt', 'beep boop\n' );
  }

  can be replaced by an approach which addresses existence via error handling.

  var writeFile = require( '@stdlib/fs-write-file' );
  
  // Explicitly handle the error...
  var err = writeFile.sync( '/path/to/file.txt', 'beep boop\n' );
  if ( err instanceof Error ) {
      // You choose what to do...
      throw err;
  }

Examples

var join = require( 'path' ).join;
var writeFile = require( '@stdlib/fs-write-file' );

var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' );

// Synchronously write data to a file:
var err = writeFile.sync( fpath, 'beep boop\n', 'utf8' );
// returns null

console.log( err instanceof Error );
// => false

// Asynchronously write data to a file:
writeFile( fpath, 'beep boop\n', onWrite );

function onWrite( error ) {
    if ( error ) {
        console.error( 'Error: %s', error.message );
    }
    console.log( 'Success!' );
}

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CLI

Installation

To use as a general utility, install the CLI package globally

npm install -g @stdlib/fs-write-file-cli

Usage

Usage: write-file [options] <filepath>

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
  --enc, --encoding encoding   Encoding. Default: 'utf8'.
         --flag flag           Flag. Default: 'r'.
         --mode mode           Mode. Default: 0o666.

Notes

• Relative output file paths are resolved relative to the current working directory.
• Errors are written to stderr.
• File contents should be provided over stdin as part of a standard stream pipeline.

Examples

$ printf 'beep boop\n' | write-file ./examples/fixtures/file.txt

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See Also

• @stdlib/fs-exists: test whether a path exists on the filesystem.
• @stdlib/fs-read-file: read the entire contents of a file.

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.