| name | shell-scripts |
| description | Use when creating or editing shell scripts, Bash files, deployment scripts, build scripts, or writing shell commands into files; emphasizes strict mode, portability, safety, and maintainability. |
Shell Script Best Practices
Apply these conventions to every shell script you write or modify.
Required Header
Every script must start with:
#!/bin/bash
set -euo pipefail
cd "$(dirname "$0")"
What strict mode does
| Flag | Effect |
|---|
set -e | Exit immediately on any non-zero exit code |
set -u | Treat unset variables as errors (catches typos like $BUKCET) |
set -o pipefail | Fail pipelines if any command fails, not just the last one |
Why cd "$(dirname "$0")" matters
Scripts should work regardless of where they're invoked from. This line changes to the script's own directory so relative paths (like ./build.sh or cp -r media out/) resolve correctly.
Only omit if the script genuinely needs to operate in the caller's working directory — and add a comment explaining why.
Additional Conventions
- Quote all variable expansions:
"$var", "${arr[@]}" — unquoted variables break on spaces and glob characters.
- Use
[[ ]] over [ ]: Double brackets prevent word splitting and support pattern matching.
- Prefer
$() over backticks: Clearer, nestable, and avoids escaping issues.
- No unnecessary dependencies: Prefer shell builtins over external commands when equivalent (e.g.,
[[ -f file ]] over test -f file).
