Read File

Read the entire contents of a file.

Usage

var readFile = require( '@stdlib/fs/read-file' );

readFile( file, [options,] clbk )

Asynchronously reads the entire contents of a file.

readFile( __filename, onFile );

function onFile( error, data ) {
    if ( error ) {
        throw error;
    }
    console.log( data );
}

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

readFile.sync( file[, options] )

Synchronously reads the entire contents of a file.

var out = readFile.sync( __filename );
if ( out instanceof Error ) {
    throw out;
}
console.log( out );

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

Notes

  • The difference between this API and fs.readFileSync() is that fs.readFileSync() will throw if an error is encountered (e.g., if given a non-existent path) and this API will return an error. Hence, the following anti-pattern
```javascript
var fs = require( 'fs' );

var file = '/path/to/file.js';

// Check for existence to prevent an error being thrown...
if ( fs.existsSync( file ) ) {
    file = fs.readFileSync( file );
}
```

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

```javascript
var readFile = require( '@stdlib/fs/read-file' );

var file = '/path/to/file.js';

// Explicitly handle the error...
file = readFile.sync( file );
if ( file instanceof Error ) {
    // You choose what to do...
    console.error( file.message );
}
```

Examples

var readFile = require( '@stdlib/fs/read-file' );

/* Sync */

var file = readFile.sync( __filename, 'utf8' );
// returns <string>

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

file = readFile.sync( 'beepboop', {
    'encoding': 'utf8'
});
// returns <Error>

console.log( file instanceof Error );
// => true


/* Async */

readFile( __filename, onFile );
readFile( 'beepboop', onFile );

function onFile( error, data ) {
    if ( error ) {
        if ( error.code === 'ENOENT' ) {
            console.error( 'File does not exist.' );
        } else {
            throw error;
        }
    } else {
        console.log( data );
    }
}

CLI

Usage

Usage: readfile [options] <filepath>

Options:

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

Notes

  • Relative file paths are resolved relative to the current working directory.
  • Errors are written to stderr.
  • File contents are written to stdout.

Examples

$ readfile ./README.md
<file_contents>