Git pre-commit check to stop accidental commits to master/main/develop branches.

install-pre-commit.sh

#!/bin/bash
# This gist contains pre-commit hooks to prevent you from commiting bad code or to the wrong branch.
# There are six variants that I have built:
# - pre-commit: stops commits to master/main/develop branches.
# - pre-commit-2: also includes a core.whitespace check.
# - pre-commit-3: the core.whitespace check and an EOF-newline-check.
# - pre-commit-4: only the core.whitespace check.
# - pre-commit-5: elixir formatting check.
# - pre-commit-6: prettier formatting check.
# Set the desired version like this before proceeding:
# FILE=pre-commit

# Install in current Git repo only:
# curl -fL https://gist.githubusercontent.com/stefansundin/9059706/raw/install-pre-commit.sh | sh -s ${FILE:-pre-commit}
# Uninstall:
# rm .git/hooks/pre-commit

# Global installation instructions: (requires git 2.9 or later)
# NOTE: if you configure core.hooksPath, then git will only run the hooks from that directory (and will ignore repo-specific hooks in .git/hooks/).
# mkdir $HOME/.githooks
# git config --global core.hooksPath $HOME/.githooks
# curl -fL -o $HOME/.githooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/${FILE:-pre-commit}
# chmod +x $HOME/.githooks/pre-commit
# Uninstall:
# rm $HOME/.githooks/pre-commit

GIT_DIR=`git rev-parse --git-common-dir 2> /dev/null`

>&2 echo
>&2 echo

if [ "$GIT_DIR" == "" ]; then
  >&2 echo "This does not appear to be a git repo."
  exit 1
fi

if [ -f "$GIT_DIR/hooks/pre-commit" ]; then
  >&2 echo "There is already a pre-commit hook installed. Delete it first."
  >&2 echo
  >&2 echo "    rm '$GIT_DIR/hooks/pre-commit'"
  >&2 echo
  exit 2
fi

FILE=${1:-pre-commit}

>&2 echo "Downloading $FILE hook from https://gist.github.com/stefansundin/9059706"
>&2 echo

curl -fL -o "$GIT_DIR/hooks/pre-commit" "https://gist.githubusercontent.com/stefansundin/9059706/raw/$FILE"
if [ ! -f "$GIT_DIR/hooks/pre-commit" ]; then
  >&2 echo "Error downloading pre-commit script!"
  exit 3
fi

chmod +x "$GIT_DIR/hooks/pre-commit"

>&2 echo
>&2 echo "You're all set!"
>&2 echo "P.S. There is now a way to install this globally, see the instructions on the gist page."

exit 0

pre-commit

#!/bin/bash
# Stops accidental commits to master/main/develop. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit
# chmod +x .git/hooks/pre-commit

BRANCH=`git rev-parse --abbrev-ref HEAD`

if [[ "$BRANCH" =~ ^(master|main|develop)$ ]]; then
  >&2 echo "You are on branch $BRANCH. Are you sure you want to commit to this branch?"
  >&2 echo "If so, commit with -n to bypass this pre-commit hook."
  exit 1
fi

exit 0

pre-commit-2

#!/bin/bash
# Stops accidental commits to master/main/develop. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit-2
# chmod +x .git/hooks/pre-commit

BRANCH=`git rev-parse --abbrev-ref HEAD`

if [[ "$BRANCH" =~ ^(master|main|develop)$ ]]; then
  >&2 echo "You are on branch $BRANCH. Are you sure you want to commit to this branch?"
  >&2 echo "If so, commit with -n to bypass this pre-commit hook."
  exit 1
fi

if [ "`git diff --check --cached | wc -c`" -gt 0 ]; then
  >&2 echo "Your spaces don't agree with your core.whitespace rules."
  >&2 echo 'Please run `git diff --check HEAD` to see your errors.'
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 2
fi

exit 0

pre-commit-3

#!/bin/bash
# Stops accidental commits to master/main/develop. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit-3
# chmod +x .git/hooks/pre-commit

BRANCH=`git rev-parse --abbrev-ref HEAD`

if [[ "$BRANCH" =~ ^(master|main|develop)$ ]]; then
  >&2 echo "You are on branch $BRANCH. Are you sure you want to commit to this branch?"
  >&2 echo "If so, commit with -n to bypass this pre-commit hook."
  exit 1
fi

if [ "`git diff --check --cached | wc -c`" -gt 0 ]; then
  >&2 echo "Your spaces don't agree with your core.whitespace rules."
  >&2 echo 'Please run `git diff --check HEAD` to see your errors.'
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 2
fi


NOEOF=()
FILES=`git status --porcelain | grep "^M" | cut -b4-`

while read -r f; do
  if [ "`tail -c 1 $f`" != "" ]; then
    NOEOF+=("$f")
  fi
done <<< "$FILES"

if [ ${#NOEOF[@]} -gt 0 ]; then
  >&2 echo "No newlines at the end of these files:"
  for f in "${NOEOF[@]}"; do
    >&2 echo "  $f"
  done
  >&2 echo
  >&2 echo "To check your whole repository, run this:"
  >&2 echo
  >&2 echo '    git ls-tree -r -z --name-only HEAD | xargs -0 file | grep text | cut -d: -f1 | xargs -I {} bash -c '\''if [ -n "`tail -c 1 "{}"`" ]; then echo {}; fi'\'''
  >&2 echo
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 3
fi

exit 0

pre-commit-4

#!/bin/bash
# Checks yo whitespace on commit. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit-4
# chmod +x .git/hooks/pre-commit

if [ "`git diff --check --cached | wc -c`" -gt 0 ]; then
  >&2 echo "Your spaces don't agree with your core.whitespace rules."
  >&2 echo 'Please run `git diff --check HEAD` to see your errors.'
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 2
fi

exit 0

pre-commit-5

#!/bin/bash
# Checks elixir formatting on commit. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit-5
# chmod +x .git/hooks/pre-commit

if [ "`git diff --check --cached | wc -c`" -gt 0 ]; then
  >&2 echo "Your spaces don't agree with your core.whitespace rules."
  >&2 echo 'Please run `git diff --check HEAD` to see your errors.'
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 2
fi

mix format --check-formatted || {
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 3
}

exit 0

pre-commit-6

#!/bin/bash
# Checks prettier formatting on commit. https://gist.github.com/stefansundin/9059706
# Install:
# cd path/to/git/repo
# curl -fL -o .git/hooks/pre-commit https://gist.githubusercontent.com/stefansundin/9059706/raw/pre-commit-6
# chmod +x .git/hooks/pre-commit

if [ "`git diff --check --cached | wc -c`" -gt 0 ]; then
  >&2 echo "Your spaces don't agree with your core.whitespace rules."
  >&2 echo 'Please run `git diff --check HEAD` to see your errors.'
  >&2 echo "You can commit with -n to bypass this pre-commit hook."
  exit 2
fi

# https://prettier.io/docs/en/precommit.html#option-6-shell-script
jsfiles=$(git diff --cached --name-only --diff-filter=ACMR "*.js" "*.jsx" "*.ts" "*.tsx" "*.gql" | tr '\n' ' ')
[ -z "$jsfiles" ] && exit 0
jsfiles=$(echo "$jsfiles" | xargs ./node_modules/.bin/prettier -l)
[ -z "$jsfiles" ] && exit 0

>&2 echo "The following files do not conform to prettier formatting:"
>&2 echo "$jsfiles"
>&2 echo
>&2 echo "See the problem in each file with the following:"
echo "$jsfiles" | while read -r file; do
  >&2 echo "prettier '$file' | diff '$file' -"
done
>&2 echo
>&2 echo "Apply changes with the following:"
echo "$jsfiles" | while read -r file; do
  >&2 echo "prettier --write '$file'"
done
>&2 echo
>&2 echo "Don't forget to run 'git add' afterwards!"
>&2 echo "You can commit with -n to bypass this pre-commit hook."

exit 3

For warnings and errors, it would be good to use echo with >&2 to send the messages to stderr.

thanks a lot

@felipe1982 Done. 👍