Published on May 2nd, 2015 | by MaxiSoler0
[New Tool] ShellCheck v0.3.7 Shell Script Static Analysis Tool
ShellCheck is a static analysis and linting tool for sh/bash scripts. It’s mainly focused on handling typical beginner and intermediate level syntax errors and pitfalls where the shell just gives a cryptic error message or strange behavior, but it also reports on a few more advanced issues where corner cases can cause delayed failures. Licensed under GPLv3.
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.
- ShellCheck is written in Haskell, and requires 2 GB of memory to compile.
What does ShellCheck check?
Here is an incomplete list of things ShellCheck warns about and suggests improvements to:
Unquoted globs for find/grep Constant test expressions Assigning arrays to strings Redirecting into source file Existence checks of globs Globs in regex context PS1 colors not in \[..\] Prematurely terminated find -exec Literal quotes in arguments Assignment in subshells Confusing time(1) for builtin ~ in quotes Single, quoted 'for' argument Arithmetic truncation Functions used externally Unused variables Looping over ls output Arguments in aliases Referencing arrays as strings Unquoted command expansion $ in for loop variables Unquoted $@ Unicode quotes Attempted redirection of stdout+stderr Attempted indirect assignment Attempted indirect reference Variables in single quotes Comparing numbers with < or > Unsupported [ ] operators Using ~ in $PATH Quoted =~ regex Opportunities for grep -q Tautology due to spacing Variable brace expansion (Bash) Commands eating loop input Decimals arithmetics Comma separated arrays Misused 'exec' Globs that could become options Common shebang errors Variables in printf format Numerical comparison of strings Prefix assignments in args Implicit precedence in find Useless use of echo Repetitive redirections Redirecting sudo  around ranges in tr Misquoted traps && in [ .. ] Masked return values Singlequote closed by apostrophe Attempting to escape ' in '' Misused char class globs Concatenating strings and arrays. Positional parameter misreference cd-and-back antipattern Missing semicolons in loops Catastrophic rm $ in assignments Aliases expanding early Spaces in assignment Features shebang may not support Excessive $()/``