Append File

Append data to a file.

Usage

var appendFile = require( '@stdlib/fs/append-file' );

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

Asynchronously appends data to a file.

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

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

appendFile( fpath, 'beep boop\n', onAppend );

function onAppend( error ) {
    if ( error ) {
        console.log( error instanceof Error );
        // => false
    }
}

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' );

appendFile( fpath, string2buffer( 'beep boop\n' ), onAppend );

function onAppend( error ) {
    if ( error ) {
        console.log( error instanceof Error );
        // => false
    }
}

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

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

Synchronously appends data to a file.

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

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

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

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

Notes

The difference between this appendFile.sync and fs.appendFileSync() is that fs.appendFileSync() 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.appendFileSync( '/path/to/file.txt', 'beep boop\n' );
}

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

var appendFile = require( '@stdlib/fs/append-file' );

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

Examples

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

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

// Synchronously append data to a file:

var error = appendFile.sync( fpath, 'beep boop\n', 'utf8' );
// Function successfully executes and returns null

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

// Asynchronously append data to a file:

appendFile( fpath, 'beep boop\n', onAppend );

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

CLI

Usage

Usage: append-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: 'a'.
         --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' | append-file ./examples/fixtures/file.txt