Bash resources

Some resources to help me write good (or at least better) Bash scripts.

Please see the accompanying template.

• Template - Template for starting new scripts.
• Snippets - Reusable snippets.
• Scripts - A collection of full scripts.

Tips

• Use a recent version of Bash.
  • MacOS (at the time of writing) uses an old version of Bash by default (3.2). Upgrade with e.g. brew install bash.

Writing scripts

Tips for writing scripts, as opposed to interactive command line use.

• Use ShellCheck.
• Always prefer long form parameters (e.g. --long-form) over short form (e.g. -l).
  • This makes scripts much more readable.
• Prefix variables with local inside functions.
  • Variables are globally scoped by default. This reduces the scope to just the function.

Tricks

• Variable length arguments list
  • Use an array: some_cmd "${args[@]}"
• Empty array expansion when using nounset
  • To support Bash <4.4: ${arr[@]+"${arr[@]}"}

Resources

• ShellCheck
• Writing Robust Bash Shell Scripts
• Minimal safe Bash script template
• Shell Script Best Practices
• Safer bash scripts with 'set -euxo pipefail'
• Writing Shell Scripts
  • Parameter parsing
• Advanced Bash Scripting Guide
  • Parameter substitution