This GIT hook populates the commit message with a prefix like [TASK] and suffix which contains the ticket number. It takes this information from the branch name. A branch name task/1234 will create a message: [TASK] (1234))

prepare-commit-msg.sh

#!/bin/bash

COMMIT_MSG_FILE=$1
COMMIT_SOURCE=$2
SHA1=$3

# Only do something when we ARE NOT amending a commit!
if [ ! ${SHA1} ]; then

	# We are only interesed in feature branches like feature/foo
	if [ -z "$BRANCES_TO_SKIP" ]; then
		BRANCHES_TO_SKIP=(master develop)
	fi

	# Get the current branch name
	BRANCH_NAME=$(git symbolic-ref --short HEAD)

	# Get the first part of the branch name: foo/bar -> foo
	# This is considered the type of the feature branch like bugfix, feature, task
	FEATURE_BRANCH="${BRANCH_NAME%/*}"
	FEATURE_BRANCH=$(tr '[:lower:]' '[:upper:]' <<< "$FEATURE_BRANCH")

	# Get the last part of the branch name: foo/bar -> bar
	# This is considered the JIRA issue number.
	BRANCH_NAME="${BRANCH_NAME##*/}"
	BRANCH_NAME=$(tr '[:lower:]' '[:upper:]' <<< "$BRANCH_NAME")
	
	# When there are no digits in the second part or there is no second part, we do not have a ticket -> (-)
	if [[ ! $BRANCH_NAME =~ [0-9] ]] || [ ! $BRANCH_NAME ]; then
		BRANCH_NAME="-"
	fi

	BRANCH_EXCLUDED=$(printf "%s\n" "${BRANCHES_TO_SKIP[@]}" | grep -c "^$BRANCH_NAME$")
	BRANCH_IN_COMMIT=$(grep -c "\[$BRANCH_NAME\]" $1)

	if [ -n "$FEATURE_BRANCH" ]; then
		sed -i.bak -e "1s/^/[$FEATURE_BRANCH] ($BRANCH_NAME)/" $1 
	fi
fi