shellcheck

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# ShellCheck - A shell script static analysis tool

ShellCheck is a GPLv3 tool that gives warnings and suggestions for bash/sh shell scripts:

![Screenshot of a terminal showing problematic shell script lines highlighted](doc/terminal.png)

The goals of ShellCheck are

* To point out and clarify typical beginner's syntax issues that cause a shell
  to give cryptic error messages.

* To point out and clarify typical intermediate level semantic problems that
  cause a shell to behave strangely and counter-intuitively.

* To point out subtle caveats, corner cases and pitfalls that may cause an
  advanced user's otherwise working script to fail under future circumstances.

See [the gallery of bad code](README.md#user-content-gallery-of-bad-code) for examples of what ShellCheck can help you identify!

## Table of Contents

* [How to use](#how-to-use)
  * [On the web](#on-the-web)
  * [From your terminal](#from-your-terminal)
  * [In your editor](#in-your-editor)
  * [In your build or test suites](#in-your-build-or-test-suites)
* [Installing](#installing)
* [Compiling from source](#compiling-from-source)
  * [Installing Cabal](#installing-cabal)
  * [Compiling ShellCheck](#compiling-shellcheck)
  * [Running tests](#running-tests)
* [Gallery of bad code](#gallery-of-bad-code)
  * [Quoting](#quoting)
  * [Conditionals](#conditionals)
  * [Frequently misused commands](#frequently-misused-commands)
  * [Common beginner's mistakes](#common-beginners-mistakes)
  * [Style](#style)
  * [Data and typing errors](#data-and-typing-errors)
  * [Robustness](#robustness)
  * [Portability](#portability)
  * [Miscellaneous](#miscellaneous)
* [Testimonials](#testimonials)
* [Ignoring issues](#ignoring-issues)
* [Reporting bugs](#reporting-bugs)
* [Contributing](#contributing)
* [Copyright](#copyright)
* [Other Resources](#other-resources)

## How to use

There are a number of ways to use ShellCheck!

### On the web

Paste a shell script on <https://www.shellcheck.net> for instant feedback.

[ShellCheck.net](https://www.shellcheck.net) is always synchronized to the latest git commit, and is the easiest way to give ShellCheck a go. Tell your friends!

### From your terminal

Run `shellcheck yourscript` in your terminal for instant output, as seen above.

### In your editor

You can see ShellCheck suggestions directly in a variety of editors.

* Vim, through [ALE](https://github.com/w0rp/ale), [Neomake](https://github.com/neomake/neomake), or [Syntastic](https://github.com/scrooloose/syntastic):

![Screenshot of Vim showing inlined shellcheck feedback](doc/vim-syntastic.png).

* Emacs, through [Flycheck](https://github.com/flycheck/flycheck) or [Flymake](https://github.com/federicotdn/flymake-shellcheck):

![Screenshot of emacs showing inlined shellcheck feedback](doc/emacs-flycheck.png).

* Sublime, through [