jungho-git/shell

Shell

• Shared examples and formatting reference: references/EXAMPLE.md.
• Keep new guidance, snippets, and edits aligned with that file.

Scope

Use this rule when:

• editing .sh or .bash scripts
• composing command pipelines or subshells
• handling user input, paths, permissions, or exit codes in shell

Shell code should avoid word splitting, unsafe command construction, and hidden failure.

Core Rules

• Quote variables: "$var".
• Use $(...) for command substitution.
• Prefer [[ ]] in Bash scripts.
• Never use eval.
• Use arrays for command arguments in Bash.
• Use set -euo pipefail at the top of non-interactive Bash scripts.
• Use local for function-scoped variables.
• Do not rely on cd side effects; use subshells or restore directories.
• Declare the interpreter explicitly.

Portability

• Use Bash-specific syntax only in scripts with a Bash shebang.
• For POSIX sh, avoid arrays and Bash-only [[ ]].
• Keep portability decisions explicit in the shebang and surrounding code.

Security

• Never interpolate unsanitized user input into command strings.
• Pass arguments as array elements.
• Avoid chmod 777; use minimum required permissions.
• Treat globs and word splitting as hazards.

Formatting

• Use multiline if/then/fi, for/do/done, and while/do/done blocks.
• Do not write collapsed single-line control flow.
• Prefer early return or exit for guard checks.
• Never vertically align assignments or command arguments.
• Keep compact standard style.

Validation Focus

• unquoted expansions
• exit-code handling
• word splitting or glob expansion
• current-shell vs subshell scope
• interpreter compatibility