Agent Skills: Bash Quality Gate

Bash Quality Gate

Run a standardized set of shell script quality checks. Auto-fix what's fixable, report the rest with specific locations.

Prerequisites

Verify these tools are available before running checks. Both are installed via Homebrew.

• shfmt — shell formatter (brew install shfmt)
• shellcheck — static analysis (brew install shellcheck)

Check Sequence

Run checks in this order. Formatting first so shellcheck analyzes clean code.

1. Format (auto-fix)

Run shfmt -w -i 2 -ci -bn . on all .sh files — report which files were modified. If no files changed, report "formatting clean."

Flags:

• -i 2 — 2-space indent
• -ci — indent switch cases
• -bn — binary ops start of line

If a project has an .editorconfig, shfmt picks it up automatically — skip the explicit flags.

2. Lint (report)

Run shellcheck -x *.sh **/*.sh — report issues with file, line, rule code, and severity. The -x flag follows source directives.

If scripts lack a shebang, shellcheck defaults to sh. Note any scripts missing shebangs and suggest adding them.

3. Portability (report)

Run shellcheck --shell=sh *.sh **/*.sh — check POSIX compliance. Report bash-specific constructs that would break on sh/dash. Skip this step if all scripts explicitly declare #!/bin/bash or #!/usr/bin/env bash — they've opted into bash.

Output

After all checks complete, present a summary table:

| Check       | Status | Details              |
|-------------|--------|----------------------|
| shfmt       | FIXED  | 2 files formatted    |
| shellcheck  | WARN   | 3 issues (1 error)   |
| portability | SKIP   | All scripts use bash |

Then list specific issues grouped by file, with line numbers and ShellCheck codes (e.g., SC2086). Offer to fix reported issues if the user wants.

Gate Criteria

The gate passes when all of these are true:

• shfmt reports no formatting differences (or auto-fixed successfully)
• shellcheck reports zero errors (severity: error)
• All scripts have a shebang line

The gate fails if any shellcheck error-severity issues remain after the run.

Advisory (non-blocking): warnings and info-level shellcheck findings. Report them but don't fail the gate.

| Severity | ShellCheck Flag | Gate Impact | | -------- | --------------- | ----------- | | error | (default) | Blocks | | warning | -S warning | Advisory | | info | -S info | Advisory | | style | -S style | Advisory |

File Discovery

• Find scripts by extension: *.sh
• Find scripts by shebang: #!/bin/bash, #!/bin/sh, #!/usr/bin/env bash
• Check the current directory and subdirectories
• Skip node_modules/, .git/, and vendor/ directories

Do not use when

• Checking code in another language — use the matching go-quality-gate, python-quality-gate, or typescript-quality-gate
• Deep structural refactoring (SOLID, duplication, complexity) — use refactor-clean
• Reviewing a staged or branch diff — use diff-review