ShellJS - Unix shell commands for Node.js Build Status

ShellJS is a portable (Windows included) implementation of Unix shell commands on top of the Node.js API. You can use it to eliminate your shell script's dependency on Unix while still keeping its familiar and powerful commands. You can also install it globally so you can run it from outside Node projects - say goodbye to those gnarly Bash scripts!

The project is unit-tested and battled-tested in projects like:

  • PDF.js - Firefox's next-gen PDF reader
  • Firebug - Firefox's infamous debugger
  • JSHint - Most popular JavaScript linter
  • Yeoman - Web application stack and development tool
  • - Open source PaaS for quick API backend generation

and many more.


Via npm:

$ npm install [-g] shelljs

If the global option -g is specified, the binary shjs will be installed. This makes it possible to run ShellJS scripts much like any shell script from the command line, i.e. without requiring a node_modules folder:

$ shjs my_script

You can also just copy shell.js into your project's directory, and require() accordingly.




if (!which('git')) {
  echo('Sorry, this script requires git');

// Copy files to release dir
mkdir('-p', 'out/Release');
cp('-R', 'stuff/', 'out/Release');

// Replace macros in each .js file
ls('.js').forEach(function(file) {
  sed('-i', 'BUILD_VERSION', 'v0.1.2', file);
  sed('-i', /.REMOVE_THIS_LINE.\n/, '', file);
  sed('-i', /.REPLACE_LINE_WITH_MACRO.\n/, cat('macro.js'), file);

// Run external tool synchronously
if (exec('git commit -am "Auto-commit"').code !== 0) {
  echo('Error: Git commit failed');


require 'shelljs/global'

if not which 'git'
  echo 'Sorry, this script requires git'
  exit 1

# Copy files to release dir
mkdir '-p', 'out/Release'
cp '-R', 'stuff/', 'out/Release'

# Replace macros in each .js file
cd 'lib'
for file in ls '.js'
  sed '-i', 'BUILD_VERSION', 'v0.1.2', file
  sed '-i', /.REMOVE_THIS_LINE.\n/, '', file
  sed '-i', /.REPLACE_LINE_WITH_MACRO.\n/, cat 'macro.js', file
cd '..'

# Run external tool synchronously
if (exec 'git commit -am "Auto-commit"').code != 0
  echo 'Error: Git commit failed'
  exit 1

Global vs. Local

The example above uses the convenience script shelljs/global to reduce verbosity. If polluting your global namespace is not desirable, simply require shelljs.


var shell = require('shelljs');
shell.echo('hello world');

Make tool

A convenience script shelljs/make is also provided to mimic the behavior of a Unix Makefile. In this case all shell objects are global, and command line arguments will cause the script to execute only the corresponding function in the global target object. To avoid redundant calls, target functions are executed only once per script.

Example (CoffeeScript):

require 'shelljs/make'

target.all = ->

target.bundle = ->
  cd dirname
  mkdir 'build'
  cd 'lib'
  (cat '*.js').to '../build/output.js' = ->
  cd dirname
  mkdir 'docs'
  cd 'lib'
  for file in ls '*.js'
    text = grep '//@', file     # extract special comments
    text.replace '//@', ''      # remove comment tags 'docs/'

To run the target all, call the above script without arguments: $ node make. To run the target docs: $ node make docs, and so on.

Command reference

All commands run synchronously, unless otherwise stated.


Changes to directory dir for the duration of the script


Returns the current directory.

ls([options ,] path [,path ...])

ls([options ,] path_array)

Available options:

  • -R: recursive
  • -A: all files (include files beginning with ., except for . and ..)


ls('-R', '/users/me', '/tmp');
ls('-R', ['/users/me', '/tmp']); // same as above

Returns array of files in the given path, or in current directory if no path provided.

find(path [,path ...])



find('src', 'lib');
find(['src', 'lib']); // same as above
find('.').filter(function(file) { return file.match(/.js$/); });

Returns array of all files (however deep) in the given paths.

The main difference from ls('-R', path) is that the resulting file names include the base directories, e.g. lib/resources/file1 instead of just file1.

cp([options ,] source [,source ...], dest)

cp([options ,] source_array, dest)

Available options:

  • -f: force
  • -r, -R: recursive


cp('file1', 'dir1');
cp('-Rf', '/tmp/', '/usr/local/', '/home/tmp');
cp('-Rf', ['/tmp/', '/usr/local/'], '/home/tmp'); // same as above

Copies files. The wildcard * is accepted.

rm([options ,] file [, file ...])

rm([options ,] file_array)

Available options:

  • -f: force
  • -r, -R: recursive


rm('-rf', '/tmp/*');
rm('some_file.txt', 'another_file.txt');
rm(['some_file.txt', 'another_file.txt']); // same as above

Removes files. The wildcard * is accepted.

mv(source [, source ...], dest')

mv(source_array, dest')

Available options:

  • f: force


mv('-f', 'file', 'dir/');
mv('file1', 'file2', 'dir/');
mv(['file1', 'file2'], 'dir/'); // same as above

Moves files. The wildcard * is accepted.

mkdir([options ,] dir [, dir ...])

mkdir([options ,] dir_array)

Available options:

  • p: full path (will create intermediate dirs if necessary)


mkdir('-p', '/tmp/a/b/c/d', '/tmp/e/f/g');
mkdir('-p', ['/tmp/a/b/c/d', '/tmp/e/f/g']); // same as above

Creates directories.


Available expression primaries:

  • '-b', 'path': true if path is a block device
  • '-c', 'path': true if path is a character device
  • '-d', 'path': true if path is a directory
  • '-e', 'path': true if path exists
  • '-f', 'path': true if path is a regular file
  • '-L', 'path': true if path is a symboilc link
  • '-p', 'path': true if path is a pipe (FIFO)
  • '-S', 'path': true if path is a socket


if (test('-d', path)) { / do something with dir / };
if (!test('-f', path)) continue; // skip if it's a regular file

Evaluates expression using the available primaries and returns corresponding value.

cat(file [, file ...])



var str = cat('file*.txt');
var str = cat('file1', 'file2');
var str = cat(['file1', 'file2']); // same as above

Returns a string containing the given file, or a concatenated string containing the files if more than one file is given (a new line character is introduced between each file). Wildcard * accepted.




Analogous to the redirection operator > in Unix, but works with JavaScript strings (such as those returned by cat, grep, etc). Like Unix redirections, to() will overwrite any existing file!

sed([options ,] search_regex, replace_str, file)

Available options:

  • -i: Replace contents of 'file' in-place. Note that no backups will be created!


sed('-i', 'PROGRAM_VERSION', 'v0.1.3', 'source.js');
sed(/.DELETE_THIS_LINE.\n/, '', 'source.js');

Reads an input string from file and performs a JavaScript replace() on the input using the given search regex and replacement string. Returns the new string after replacement.

grep([options ,] regex_filter, file [, file ...])

grep([options ,] regex_filter, file_array)

Available options:

  • -v: Inverse the sense of the regex and print the lines not matching the criteria.


grep('-v', 'GLOBAL_VARIABLE', '.js');
grep('GLOBAL_VARIABLE', '.js');

Reads input string from given files and returns a string containing all lines of the file that match the given regex_filter. Wildcard * accepted.



var nodeExec = which('node');

Searches for command in the system's PATH. On Windows looks for .exe, .cmd, and .bat extensions. Returns string containing the absolute path to the command.

echo(string [,string ...])


echo('hello world');
var str = echo('hello world');

Prints string to stdout, and returns string with additional utility methods like .to().


Exits the current process with the given exit code.


Object containing environment variables (both getter and setter). Shortcut to process.env.

exec(command [, options] [, callback])

Available options (all false by default):

  • async: Asynchronous execution. Defaults to true if a callback is provided.
  • silent: Do not echo program output to console.


var version = exec('node --version', {silent:true}).output;

var child = exec('some_long_running_process', {async:true});
child.stdout.on('data', function(data) { 
  / ... do something with data ... / 

exec('some_long_running_process', function(code, output) {
  console.log('Exit code:', code);
  console.log('Program output:', output);

Executes the given command synchronously, unless otherwise specified. When in synchronous mode returns the object { code:..., output:... }, containing the program's output (stdout + stderr) and its exit code. Otherwise returns the child process object, and the callback gets the arguments (code, output).

Note: For long-lived processes, it's best to run exec() asynchronously as the current synchronous implementation uses a lot of CPU. This should be getting fixed soon.




var silentState = config.silent; // save old silent state
config.silent = true;
/ ... /
config.silent = silentState; // restore old silent state

Suppresses all command output if true, except for echo() calls. Default is false.



config.fatal = true;
cp('this_file_does_not_exist', '/dev/null'); // dies here
/ more commands... /

If true the script will die on errors. Default is false.

Non-Unix commands


Searches and returns string containing a writeable, platform-dependent temporary directory. Follows Python's tempfile algorithm.


Tests if error occurred in the last command. Returns null if no error occurred, otherwise returns string explaining the error