Hook Types

Updated

October 30, 2026

Hook Types: Pre-Commit, Commit-Msg, Pre-Push

After this page you can name the client hooks this book uses and where they live on Linux.

A hook is a program Git runs

Executable files in .git/hooks/. Git looks at the filename. If pre-commit exists and is executable (chmod +x), Git runs it before it writes a commit object. Exit status 0 continues. Non-zero aborts.

 git commit
    │
    ▼
 pre-commit      exit ≠ 0 ──► abort, no object
    │ 0
    ▼
 commit-msg      exit ≠ 0 ──► abort, no object
    │ 0
    ▼
 commit object written, main slides forward

 git push
    │
    ▼
 pre-push        exit ≠ 0 ──► abort, remote unchanged
    │ 0
    ▼
 objects uploaded

Sample files are *.sample and are not run. Copy and chmod:

cd ~/desk/desk-api
ls .git/hooks
install -m 0755 .git/hooks/pre-commit.sample .git/hooks/pre-commit
# then edit; or write your own

install -m 0755 is the Linux way to copy and set the executable bit in one step.

Client hooks you will write

Hook	When	Typical job
`pre-commit`	After you type `git commit`, before the object exists	Lint, block secrets, `git diff --check`
`commit-msg`	After you save the message	Conventional Commits pattern
`pre-push`	After you type `git push`, before objects upload	Tests, block WIP branches

There are more (prepare-commit-msg, post-commit, post-checkout). Start with these three.

Server hooks (later)

A forge runs pre-receive / update / post-receive on the server when you push. Chapter 23 names them; chapter 31 uses them for policy. Your laptop hooks do not run on the server. A teammate can skip pre-commit with git commit --no-verify. Server hooks are the ones that actually enforce.

Environment

Hooks run with a POSIX shell on Linux unless the shebang says otherwise. Always start with:

#!/usr/bin/env bash
set -euo pipefail

Git sets GIT_DIR and runs with the working tree as cwd for client hooks (with nuances for worktrees, chapter 14). Print to stderr so you do not pollute commit output:

echo "pre-commit: running" >&2