An automatic check that runs after the agent writes or edits a file. It uses ShellCheck for shell scripts and Ruff for Python files.

It checks edited .sh files with ShellCheck and automatically fixes Ruff-detectable issues in edited .py files.

It catches common script and code problems immediately after changes, so errors are less likely to remain unnoticed.

PostToolUse — Hook by brujack

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/brujack/dotfiles/post-tool-use

Clone the repo

git clone --depth 1 https://github.com/brujack/dotfiles

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 1 finding. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

PostToolUse scanned grade A with 1 finding 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 yesterday.

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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

"command": "python3 -c \"import json,sys,subprocess; d=json.load(sys.stdin); p=d.get('tool_input',{}).get('file_path',''); subprocess.run(['shellcheck', p]) if p and p.endswith('.sh') else None\""

.claude/settings.json · 17 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Write|Edit|MultiEdit",
      "hooks": [
        {
          "type": "command",
          "command": "python3 -c \"import json,sys,subprocess; d=json.load(sys.stdin); p=d.get('tool_input',{}).get('file_path',''); subprocess.run(['shellcheck', p]) if p and p.endswith('.sh') else None\""
        },
        {
          "type": "command",
          "command": "python3 -c \"import json,sys,subprocess; d=json.load(sys.stdin); p=d.get('tool_input',{}).get('file_path',''); subprocess.run(['ruff', 'check', '--fix', p]) if p and p.endswith('.py') else None\""
        }
      ]
    }
  ]
}

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.

yesterday First seen · 17 lines scan A 782f69f860d0

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository brujack/dotfiles (5 stars, last pushed 2d ago), licensed Apache-2.0. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Languages

PostToolUse

Getting it into your agent

Grade A, and why

Runs shell commandslowCapability

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

PostToolUse

SessionStart

SessionStart

PreToolUse

SessionStart

SessionStart