Git pre commit hook to add the jira ticket id to the commit message

prepare-commit-msg

#!/bin/sh

# A hook script to prepare the commit log message if the branch name starts with a JIRA ticket.
# It adds the branch name to the commit message, if it is not already part of it.
# https://stackoverflow.com/questions/5894946/how-to-add-gits-branch-name-to-the-commit-message/59831864#59831864

PROJECT_PREFIX="PROJ"  # TODO fill in project here
BRANCH_PATH=$(git symbolic-ref -q HEAD) # Something like refs/heads/branch_name
BRANCH_NAME=${BRANCH_PATH##*/}          # Get text behind the last / of the branch path

shopt -s nocasematch  # Enable case insensitive match, jira project codes are uppercase
REGEX="(${PROJECT_PREFIX}-[0-9]*)"

if [[ $BRANCH_NAME =~ $REGEX ]]; then
    # Get the captured portion of the branch name, and change it to upper case.
    # Mac bash version is 3, so can't use the `^^` to uppercase the string, using `tr` command instead.
    # If you do not need the uppercase, use the BASH_REMATCH dirrectly
    # JIRA_TICKET=${BASH_REMATCH[1]}
    JIRA_TICKET=$(echo ${BASH_REMATCH[1]} | tr [:lower:] [:upper:])
    ORIGINAL_MESSAGE=`cat $1`

    # If the message already begins with $PROJECT_NAME-#, do not edit the commit message.
    if [[ $ORIGINAL_MESSAGE == $JIRA_TICKET* ]]; then
        exit
    fi

    sed -i.bak -e "1s/^/$JIRA_TICKET: /" $1  # Insert branch name at the start of the commit message file
fi
# else => do not edit the commit message.

Instructions:

• copy to .git/hooks/prepare-commit-msg
• ensure no (global) .gitconfig has set core.hooksPath NOT to /dev/null
• ???
• Profit!