no-shell-file-ops

no-shell-file-ops

A Claude Code plugin that blocks shell commands that read or edit files — enforcing the built-in Read and Edit tools. Also hints agents to re-read files when the Edit tool fails with stale strings.

Find/grep enforcement lives in the sibling plugin: no-find-grep — blocks bare find/grep and detects common rg flag misuse.

What it does

Registers a PreToolUse hook that intercepts every Bash command before execution. It detects and blocks:

Pattern	Why	Example
sed -n	Use Read tool to view file content instead of parsing with sed	sed -n '100,200p' file
cat -A/-v/-vet	Use Read tool to inspect file content instead of shell tricks	cat -A file
xxd / od	Use Read tool to inspect file content instead of hex/octal dumps	xxd file
sed -i	Use Edit tool for file editing instead of sed in-place	sed -i 's/old/new/' file
sd	Use Edit tool for find-and-replace. sd always returns exit 0 even on no-op.	sd 'old' 'new' file
python -c with open()	Use Read/Edit tools for file operations instead of ad-hoc scripts	python3 -c "open('f').read()"

When a match is found, the hook prints a diagnostic message to stderr and exits with code 2, preventing the command from running.

Also registers a PostToolUseFailure hook on Edit: when the Edit tool fails with "String to replace not found," it provides additionalContext hinting the agent to re-read the file with the Read tool before retrying.

At session end (or /clear), the plugin reports how many commands were blocked.

Why CLAUDE.md wasn't enough

My global CLAUDE.md already says:

For file editing, use the built-in Edit tool instead of sed -i, sd, or python -c.

But Claude Code doesn't always follow instructions consistently. A hook enforces the rule at the tool level, every time, with no exceptions.

Install

Install via the marketplace:

TonyWu20/my-claude-marketplace

Or manually, register the plugin in your Claude Code settings:

{
  "plugins": {
    "no-shell-file-ops": {
      "path": "/path/to/no-shell-file-ops"
    }
  }
}

Files

File	Purpose
hooks/hooks.json	Hook registration — intercepts Bash tool calls and Edit failures
hooks/block-file-ops.sh	Shell script that blocks shell file-read and file-edit commands (enforcing Read/Edit tools)
hooks/hint-edit-reread.sh	Shell script that catches Edit tool failures and hints the agent to re-read the file via additionalContext
hooks/session-end.sh	Shell script that reports blocked-command count on session exit and /clear

Compatible with Linux and macOS. Locking uses mkdir-based mutex (no flock dependency).