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!

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

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

• PDF.js - Firefox's next-gen PDF reader
• Firebug - Firefox's infamous debugger
• JSHint & ESLint - popular JavaScript linters
• Zepto - jQuery-compatible JavaScript library for modern browsers
• Yeoman - Web application stack and development tool
• Deployd.com - Open source PaaS for quick API backend generation
• And many more.

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 in our Wiki page!

Upgrading from an older version? Check out our breaking changes 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 page or shelljs.org.

Installing

Via npm:

$ npm install [-g] shelljs

Examples

var shell = require('shelljs');
 
if (!shell.which('git')) {
  shell.echo('Sorry, this script requires git');
  shell.exit(1);
}
 
// Copy files to release dir 
shell.rm('-rf', 'out/Release');
shell.cp('-R', 'stuff/', 'out/Release');
 
// Replace macros in each .js file 
shell.cd('lib');
shell.ls('*.js').forEach(function (file) {
  shell.sed('-i', 'BUILD_VERSION', 'v0.1.2', file);
  shell.sed('-i', /^.*REMOVE_THIS_LINE.*$/, '', file);
  shell.sed('-i', /.*REPLACE_LINE_WITH_MACRO.*\n/, shell.cat('macro.js'), file);
});
shell.cd('..');
 
// Run external tool synchronously 
if (shell.exec('git commit -am "Auto-commit"').code !== 0) {
  shell.echo('Error: Git commit failed');
  shell.exit(1);
}

Global vs. Local

We no longer recommend using a global-import for ShellJS (i.e. require('shelljs/global')). While still supported for convenience, this pollutes the global namespace, and should therefore only be used with caution.

Instead, we recommend a local import (standard for npm packages):

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 page.

cat(file [, file ...])

cat(file_array)

Examples:

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).

cd([dir])

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

chmod([options,] octal_mode || octal_string, file)

chmod([options,] symbolic_mode, file)

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

Examples:

chmod(755, '/Users/brandon');
chmod('755', '/Users/brandon'); // same as above 
chmod('u+x', '/Users/brandon');
chmod('-R', 'a-w', '/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.

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

cp([options,] source_array, dest)

Available options:

• -f: force (default behavior)
• -n: no-clobber
• -u: only copy if source is newer than dest
• -r, -R: recursive
• -L: follow symlinks
• -P: don't follow symlinks

Examples:

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:

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

Arguments:

• 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.

Examples:

// 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:

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

Arguments:

• +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.

Examples:

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:

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

Arguments:

• +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

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

Available options:

• -e: interpret backslash escapes (default)

Examples:

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):

• async: Asynchronous execution. If a callback is provided, it will be set to true, regardless of the passed value.
• silent: Do not echo program output to console.
• and any option available to Node.js's child_process.exec()

Examples:

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(path_array)

Examples:

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:

• -v: Inverse the sense of the regex and print the lines not matching the criteria.
• -l: Print only filenames of matching files

Examples:

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:

• -n <num>: Show the first <num> lines of the files

Examples:

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:

• -s: symlink
• -f: force

Examples:

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:

• -R: recursive
• -A: all files (include files beginning with ., except for . and ..)
• -L: follow symlinks
• -d: list directories themselves, not their contents
• -l: list objects representing each file, each with fields containing ls -l output fields. See fs.Stats for more info

Examples:

ls('projs/*.js');
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:

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

Examples:

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:

• -f: force (default behavior)
• -n: no-clobber

Examples:

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

Moves files.

pwd()

Returns the current directory.

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

rm([options,] file_array)

Available options:

• -f: force
• -r, -R: recursive

Examples:

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:

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

Examples:

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.

Note:

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

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

set(options)

Available options:

• +/-e: exit upon error (config.fatal)
• +/-v: verbose: show all commands (config.verbose)
• +/-f: disable filename expansion (globbing)

Examples:

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:

• -r: Reverse the result of comparisons
• -n: Compare according to numerical value

Examples:

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:

• -n <num>: Show the last <num> lines of the files

Examples:

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.

tempdir()

Examples:

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

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

test(expression)

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

Examples:

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.

ShellString.prototype.to(file)

Examples:

cat('input.txt').to('output.txt');

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!

ShellString.prototype.toEnd(file)

Examples:

cat('input.txt').toEnd('output.txt');

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:

• -a: Change only the access time
• -c: Do not create any files
• -m: Change only the modification time
• -d DATE: Parse DATE and use it instead of current time
• -r FILE: Use FILE's times instead of current time

Examples:

touch('source.js');
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:

• -i: Ignore case while comparing
• -c: Prefix lines by the number of occurrences
• -d: Only print duplicate lines, one for each group of identical lines

Examples:

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

Filter adjacent matching lines from input

which(command)

Examples:

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.

exit(code)

Exits the current process with the given exit code.

error()

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.

ShellString(str)

Examples:

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()

env['VAR_NAME']

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

Pipes

Examples:

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.

Configuration

config.silent

Example:

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

Example:

require('shelljs/global');
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

Example:

config.verbose = true; // or set('-v'); 
cd('dir/');
rm('-rf', 'foo.txt', 'bar.txt');
exec('echo hello');

Will print each command as follows:

cd dir/
rm -rf foo.txt bar.txt
exec echo hello

config.globOptions

Example:

config.globOptions = {nodir: true};

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

config.reset()

Example:

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,
}

Team

Nate Fischer	Brandon Freitag