A post-tool hook that checks edited or written shell scripts with ShellCheck, a tool that finds common shell-script problems.

Use it after editing or writing `.sh` files to run ShellCheck and show up to the first 20 lines of its output.

It can reveal shell-script issues immediately after a file is changed, instead of waiting until the script is run.

PostToolUse — Hook by TypedDevs

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add hooks/typeddevs/bashunit/post-tool-use

Clone the repo

git clone --depth 1 https://github.com/TypedDevs/bashunit

Made for: Claude Code.

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

PostToolUse scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/settings.json · 13 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Edit|Write",
      "hooks": [
        {
          "type": "command",
          "command": "file=\"$CLAUDE_FILE_PATH\"; if [ -n \"$file\" ] && echo \"$file\" | grep -q '\\.sh$'; then shellcheck -x \"$file\" 2>&1 | head -20; fi"
        }
      ]
    }
  ]
}

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2d ago First seen · 13 lines scan A 1e789b4c45ae

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository TypedDevs/bashunit (424 stars, last pushed 2d ago), licensed MIT. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Testing Writing and docs assertions bash bash-script testing-framework unittesting

PostToolUse

Getting it into your agent

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

Notification

PermissionRequest

PermissionDenied

Elicitation

WorktreeRemove

CwdChanged