Portable Unix shell commands for Node.js

ShellJS - Unix shell commands for Node.js

ShellJS is a portable (Windows/Linux/OS X) 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
  • Zepto - jQuery-compatible JavaScript library for modern browsers
  • Yeoman - Web application stack and development tool
  • - Open source PaaS for quick API backend generation

and many more.

Connect with @r2r on Twitter for questions, suggestions, etc.

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

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');

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.

You can also pass arguments to your targets by using the -- separator. For example, to pass arg1 and arg2 to a target bundle, do $ node make bundle -- arg1 arg2:

target.bundle = function(argsArray) {
  // argsArray = ['arg1', 'arg2'] 
  /* ... */

All commands run synchronously, unless otherwise stated.

Changes to directory dir for the duration of the script

Returns the current directory.

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('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.

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.

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.

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.

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 symbolic 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.


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!



Analogous to the redirect-and-append operator >> in Unix, but works with JavaScript strings (such as those returned by cat, grep, etc).

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 or function. Returns the new string after replacement.

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

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

Available options:

  • -n: Suppresses the normal change of directory when adding directories to the stack, so that only the stack is manipulated.


  • dir: Makes the current working directory be the top of the stack, and then executes the equivalent of cd dir.
  • +N: Brings the Nth directory (counting from the left of the list printed by dirs, starting with zero) to the top of the list by rotating the stack.
  • -N: Brings the Nth directory (counting from the right of the list printed by dirs, starting with zero) to the top of the list by rotating the stack.


// process.cwd() === '/usr' 
pushd('/etc'); // Returns /etc /usr 
pushd('+1');   // Returns /usr /etc 

Save the current directory on the top of the directory stack and then cd to dir. With no arguments, pushd exchanges the top two directories. Returns an array of paths in the stack.

Available options:

  • -n: Suppresses the normal change of directory when removing directories from the stack, so that only the stack is manipulated.


  • +N: Removes the Nth directory (counting from the left of the list printed by dirs), starting with zero.
  • -N: Removes the Nth directory (counting from the right of the list printed by dirs), starting with zero.


echo(process.cwd()); // '/usr' 
pushd('/etc');       // '/etc /usr' 
echo(process.cwd()); // '/etc' 
popd();              // '/usr' 
echo(process.cwd()); // '/usr' 

When no arguments are given, popd removes the top directory from the stack and performs a cd to the new top directory. The elements are numbered from 0 starting at the first directory listed with dirs; i.e., popd is equivalent to popd +0. Returns an array of paths in the stack.

Available options:

  • -c: Clears the directory stack by deleting all of the elements.


  • +N: Displays the Nth directory (counting from the left of the list printed by dirs when invoked without options), starting with zero.
  • -N: Displays the Nth directory (counting from the right of the list printed by dirs when invoked without options), starting with zero.

Display the list of currently remembered directories. Returns an array of paths in the stack, or a single path if +N or -N was specified.

See also: pushd, popd

Available options:

  • s: symlink
  • f: force


ln('file', 'newlink');
ln('-sf', 'file', 'existing');

Links source to dest. Use -f to force the link, should dest already exist.

Exits the current process with the given exit code.

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

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(codeoutput) {
  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.

Available options:

  • -v: output a diagnostic for every file processed
  • -c: like verbose but report only when a change is made
  • -R: change files and directories recursively


chmod(755, '/Users/brandon');
chmod('755', '/Users/brandon'); // same as above 
chmod('u+x', '/Users/brandon');

Alters the permissions of a file or directory by either specifying the absolute permissions in octal form or expressing the changes in symbols. This command tries to mimic the POSIX behavior as much as possible. Notable exceptions:

  • In symbolic modes, 'a-r' and '-r' are identical. No consideration is given to the umask.
  • There is no "quiet" option since default behavior is to run silent.


var tmp = tempdir(); // "/tmp" for most *nix platforms 

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


var sh = require('shelljs');
var silentState = sh.config.silent; // save old silent state 
sh.config.silent = true;
/* ... */
sh.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.