Write File

Write data to a file.

Usage

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

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

Asynchronously write 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!' );
}

CLI

Usage

Usage: writefile [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' | writefile ./examples/fixtures/file.txt