The goals of ShellCheck are:

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

 * To point out and clarify typical intermediate level semantic problems,
   that causes 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.

WWW: http://www.shellcheck.net/