node package manager


tab completion helpers, for node cli programs. Inspired by npm completion.


A node package to do some custom command line<tab><tab> completion for any system command, for Bash, Zsh, and Fish shells.

Made possible using the same technique as npm (whose completion is quite awesome) relying on a shell script bridge to do the actual completion from node's land.

  • Supports zsh, fish and bash
  • CLI tool to manage and discover completion.
  • Automatic completion from package.json config
  • Or using an EventEmitter based API
  • Manual or Automatic installation using system dirs (ex. /usr/share/bash-completion/completions for bash).
  • A way to install completion script for a given shell on npm install, gently asking the user for install location.
    • tabtab install in package.json install script creates the completion file on user system.

npm install tabtab --save

You can add completion pretty easily in your node cli script:

// Ex. bin/ entry point for a "program" package 
var tab = require('tabtab')();
// General handler. Gets called on `program <tab>` and `program stuff ... <tab>` 
tab.on('program', function(data, done) {
  // General handler 
  done(null, ['foo', 'bar']);
// Specific handler. Gets called on `program list <tab>` 
tab.on('list', function(data, done) {
  done(null, ['file.js', 'file2.js']);
// Start must be called to register the completion commands and listen for 
// completion. 

These events are emitted whenever the command program completion -- .. is triggered, with special COMP_* environment variables.

tab.start() will define one command: completion for your program, which is used by the Shell completion scripts.

The data object holds interesting value to drive the output of the completion:

  • line: full command being completed
  • words: number of word
  • point: cursor position
  • partial: tabing in the middle of a word: foo bar baz bar foobarrrrrrr
  • last: last word of the line
  • lastPartial: last partial of the line
  • prev: the previous word
new Complete({
  // the String package name being completed, defaults to process.title 
  // (if not node default) or will attempt to determine parent's 
  // package.json location and extract the name from it. 
  name: 'foobar'
  // Enable / Disable cache (defaults: true) 
  cache: true,
  // Cache Time To Live duration in ms (default: 5min) 
  ttl: 1000 * 60 * 5

Completion results are cached by default, for a duration of 5 minutes. Caching is based on the value of the full command being completed (data.line).

While the EventEmitter API can offer fine control over what gets completed, completion values can be defined directly in the package.json file, using the tabtab property:

  "tabtab": {
    "nvm": ["help", "use", "install", "uninstall", "run", "current", "ls", "ls-remote"],
    "use": ["stable", "default", "iojs", "v5.11.0", "v6.0.0"]

This still requires to initialize tabtab with:


Manually loading the completion for your cli app is done very much like npm does:

. <(tabtab install --stdout --name program)

It'll enables tab-completion for the program executable. Adding it to your ~/.bashrc or ~/.zshrc will make the completions available everywhere (not only the current shell).

tabtab install --stdout --name program >> ~/.bashrc # or ~/.zshrc

This requires an additional manual step for the user. Ideally we'd want it to be automatic, and define it at a system-level.

For completions to be active for a particular command/program, the user shell (bash, zsh or fish) must load a specific file when the shell starts.

Each shell have its own system, and different loading paths. tabtab tries to figure out the most appropriate directory depending on the $SHELL variable.

  • fish Uses ~/.config/fish/completions
  • zsh Uses /usr/local/share/zsh/site-functions
  • bash Asks pkg-config for completion directories if bash-completion is installed (defaults to /usr/share/bash-completion/completions and /etc/bash_completion.d)

tabtab CLI provides an install command to ease the process of installing a completion script when the package is installed on the user system, using npm script.

Using npm's install/uninstall script, you can automatically manage completion for your program whenever it gets globally installed or removed.

  "scripts": {
    "install": "tabtab install"

On install, npm will execute the tabtab install command automatically in the context of your package.


  "name": "foobar",
  "bin": "bin/foobar",
  "scripts": {
    "install": "tabtab install"
  "dependencies": {
    "tabtab": "^1.0.0"

Nothing is done's without asking confirmation, tabtab install looks at the $SHELL variable to determine the best possible locations and uses Inquirer to ask the user what it should do:

The --auto flag can be used to bypass prompts and use the SHELL configuration file options by default:

  • bash: Will use ~/.bashrc
  • zsh: Will use ~/.zshrc
  • bash: Will use ~/.config/fish/

This way, you can silently install / uninstall completion for a specific command without asking user to do so.

The uninstall command can be used to undo what has been done by tabtab install --auto command.

todo: zsh / fish offers the ability to define description with each completion item, implemented with fish, have to adjust the same pattern to zsh.

The --completer option allows you to delegate the completion part to another program. Let's take nvm as an example.

The idea is to create a package named nvm-complete, with an executable that loads tabtab and handle the completion output of nvm-complete completion.

  "name": "nvm-complete",
  "bin": "./index.js",
  "scripts": {
    "install": "tabtab install --name nvm --completer nvm-complete"
  "dependencies": {
    "tabtab": "^1.0.0"
// index.js 
var tabtab = require('tabtab');
tabtab.on('nvm', function(data, done) {
  return done(null, ['ls', 'ls-remote', 'install', 'use', ...]);

Alternatively, we can use tabtab property in package.json file to define static list of completion results:

  "tabtab": {
    "nvm": ["help", "use", "install", "uninstall", "run", "current", "ls", "ls-remote"],
    "use": ["stable", "default", "iojs", "v5.11.0", "v6.0.0"]

For more control over the completion results, the JS api is useful for returning specific values depdending on preceding words, like completing each node versions on nvm install <tab>.

var exex = require('child_process').exec;
// To cache the list of versions returned by ls-remote 
var versions = [];
tabtab.on('install', function(data, done) {
  if (versions.length) return done(null, versions);
  // Ask nvm the list of remote, and return each as a completion item 
  exec('nvm ls-remote', function(err, stdout) {
    if (err) return done(err);
    versions = versions.concat(stdout.split(/\n/));
    return done(null, versions);

On global installation of nvm-complete, the user will be asked for installation instruction (output to stdout, write to shell config, or a system dir). The completion should be active on reload or next login (close / reopen your terminal).



On completion trigger (hitting tab), any STDOUT output is used as a completion results, and STDERR is completely silenced.

To be able to log and debug completion scripts and functions, you can use TABTAB_DEBUG environment variable. When defined, tabtab will redirect any debug output to the file specified.

export TABTAB_DEBUG=/tmp/tabtab.log

Trigger a completion, and tail -f /tmp/tabtab.log to see debugging output.

to be able to use the logger in your own completion, you can require('tabtab/lib/debug'). it is a thin wrapper on top of the debug module, and has the same api and behavior, except when process.env.tabtab_debug is defined.

const debug = require('tabtab/lib/debug')('tabtab:name');

tabtab(1) - manage and discover completion on the user system.

it provides utilities for installing a completion file, to discover and enable additional completion etc.

$ tabtab <command> [options]

  -h, --help              show this help output
  -v, --version           show package version


  install                 install and enable completion file on user system
$ tabtab install --help

  --stdout                outputs script to console and writes nothing
  --name                  program name to complete
  --completer             program that drives the completion (default: --name)

triggers the installation process and asks user for install location. --name if not defined, is determined from package.json name property. --completer can be used to delegate the completion to another program. ex.

$ tabtab install --name bower --completer bower-complete

tabtab install is not meant to be run directly, but rather used with your package.json scripts.

npm does pretty amazing stuff with its completion feature. bash and zsh provides command tab-completion, which allow you to complete the names of commands in your $path. usually these functions means bash scripting, and in the case of npm, it is partially true.

there is a special npm completion command you may want to look around, if not already.

npm completion

running this should dump this script to the console. this script works with both bash/zsh and map the correct completion functions to the npm executable. these functions takes care of parsing the comp_* variables available when hitting tab to complete a command, set them up as environment variables and run the npm completion command followed by -- words where words match value of the command being completed.

this means that using this technique npm manage to perform bash/zsh completion using node and javascript. actually, the comprehensiveness of npm completion is quite amazing.

this whole package/module is based entirely on npm's code and @isaacs work.

mit  ·  ·  @mklabs