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ShellJS - Unix shell commands for Node.js

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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!

ShellJS is proudly tested on every node release since v0.11!

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

If you have feedback, suggestions, or need help, feel free to post in our issue tracker.

Think ShellJS is cool? Check out some related projects (like
cash--a javascript-based POSIX shell)
in our Wiki page!

Upgrading from an older version? Check out our breaking
page to see
what changes to watch out for while upgrading.

Command line use

If you just want cross platform UNIX commands, checkout our new project
shelljs/shx, a utility to expose shelljs to
the command line.

For example:

$ shx mkdir -p foo
$ shx touch foo/bar.txt
$ shx rm -rf foo

A quick note about the docs

For documentation on all the latest features, check out our
README. To read docs that are consistent
with the latest release, check out the npm


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




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

// Copy files to release dir
rm('-rf', '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.*$/, '', 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');


CoffeeScript is also supported automatically:

require 'shelljs/global'

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

# Copy files to release dir
rm '-rf', '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.*$/, '', 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');

Command reference

All commands run synchronously, unless otherwise stated.
All commands accept standard bash globbing characters (*, ?, etc.),
compatible with the node glob module.

For less-commonly used commands and features, please check out our wiki

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).


Changes to directory dir for the duration of the script. Changes to home
directory if no argument is supplied.

chmod(octal_mode || octal_string, file)

chmod(symbolic_mode, file)

Available options:


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:

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

cp([options,] source_array, dest)

Available options:


cp('file1', 'dir1');
cp('-R', 'path/to/dir/', '~/newCopy/');
cp('-Rf', '/tmp/*', '/usr/local/*', '/home/tmp');
cp('-Rf', ['/tmp/*', '/usr/local/*'], '/home/tmp'); // same as above

Copies files.

pushd([options,] [dir | '-N' | '+N'])

Available options:



// 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.

popd([options,] ['-N' | '+N'])

Available options:



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.

dirs([options | '+N' | '-N'])

Available options:


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

echo([options,] string [, string ...])

Available options:


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

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

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

Available options (all false by default):


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

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, stdout, stderr) {
  console.log('Exit code:', code);
  console.log('Program output:', stdout);
  console.log('Program stderr:', stderr);

Executes the given command synchronously, unless otherwise specified. When in synchronous
mode, this returns a ShellString (compatible with ShellJS v0.6.x, which returns an object
of the form { code:..., stdout:... , stderr:... }). Otherwise, this returns the child process
object, and the callback gets the arguments (code, stdout, stderr).

Not seeing the behavior you want? exec() runs everything through sh
by default (or cmd.exe on Windows), which differs from bash. If you
need bash-specific behavior, try out the {shell: 'path/to/bash'} option.

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.

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.

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

grep([options,] regex_filter, file_array)

Available options:


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.

head([{'-n': <num>},] file [, file ...])

head([{'-n': <num>},] file_array)

Available options:


var str = head({'-n': 1}, 'file*.txt');
var str = head('file1', 'file2');
var str = head(['file1', 'file2']); // same as above

Read the start of a file.

ln([options,] source, dest)

Available options:


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

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

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

ls([options,] path_array)

Available options:


ls('-R', '/users/me', '/tmp');
ls('-R', ['/users/me', '/tmp']); // same as above
ls('-l', 'file.txt'); // { name: 'file.txt', mode: 33188, nlink: 1, ...}

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

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

mkdir([options,] dir_array)

Available options:


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.

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

mv([options ,] source_array, dest')

Available options:


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

Moves files.


Returns the current directory.

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

rm([options,] file_array)

Available options:


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

Removes files.

sed([options,] search_regex, replacement, file [, file ...])

sed([options,] search_regex, replacement, file_array)

Available options:


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

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


Like unix sed, ShellJS sed supports capture groups. Capture groups are specified
using the $n syntax:

sed(/(\w+)\s(\w+)/, '$2, $1', 'file.txt');


Available options:


set('-e'); // exit upon first error
set('+e'); // this undoes a "set('-e')"

Sets global configuration variables

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

sort([options,] file_array)

Available options:


sort('foo.txt', 'bar.txt');
sort('-r', 'foo.txt');

Return the contents of the files, sorted line-by-line. Sorting multiple
files mixes their content, just like unix sort does.

tail([{'-n': <num>},] file [, file ...])

tail([{'-n': <num>},] file_array)

Available options:


var str = tail({'-n': 1}, 'file*.txt');
var str = tail('file1', 'file2');
var str = tail(['file1', 'file2']); // same as above

Read the end of a file.



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

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


Available expression primaries:


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.



Analogous to the redirection operator > in Unix, but works with
ShellStrings (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
ShellStrings (such as those returned by cat, grep, etc).

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

touch([options,] file_array)

Available options:


touch('-c', '/path/to/some/dir/source.js');
touch({ '-r': FILE }, '/path/to/some/dir/source.js');

Update the access and modification times of each FILE to the current time.
A FILE argument that does not exist is created empty, unless -c is supplied.
This is a partial implementation of touch(1).

uniq([options,] [input, [output]])

Available options:


uniq('-i', 'foo.txt');
uniq('-cd', 'foo.txt', 'bar.txt');

Filter adjacent matching lines from input



var nodeExec = which('node');

Searches for command in the system's PATH. On Windows, this uses the
PATHEXT variable to append the extension if it's not already executable.
Returns string containing the absolute path to the command.


Exits the current process with the given exit code.


Tests if error occurred in the last command. Returns a truthy value if an
error returned and a falsy value otherwise.

Note: do not rely on the
return value to be an error message. If you need the last error message, use
the .stderr attribute from the last command's return value instead.



var foo = ShellString('hello world');

Turns a regular string into a string-like object similar to what each
command returns. This has special methods, like .to() and .toEnd()


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



grep('foo', 'file1.txt', 'file2.txt').sed(/o/g, 'a').to('output.txt');
echo('files with o\'s in the name:\n' + ls().grep('o'));
cat('test.js').exec('node'); // pipe to exec() call

Commands can send their output to another command in a pipe-like fashion.
sed, grep, cat, exec, to, and toEnd can appear on the right-hand
side of a pipe. Pipes can be chained.




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; // or set('-e');
cp('this_file_does_not_exist', '/dev/null'); // throws Error here
/* more commands... */

If true the script will throw a Javascript error when any shell.js
command encounters an error. Default is false. This is analogous to
Bash's set -e



config.verbose = true; // or set('-v');

Will print each command as follows:

cd dir/
ls subdir/



config.globOptions = {nodir: true};

Use this value for calls to glob.sync() instead of the default options.



var shell = require('shelljs');
// Make changes to shell.config, and do stuff...
/* ... */
shell.config.reset(); // reset to original state
// Do more stuff, but with original settings
/* ... */

Reset shell.config to the defaults:

  fatal: false,
  globOptions: {},
  maxdepth: 255,
  noglob: false,
  silent: false,
  verbose: false,


Nate Fischer Ari Porad
Nate Fischer Ari Porad