How to add Git's branch name to the commit message?

Question

Here is my commit-msg script as an example:

#!/bin/sh
#
# Automatically adds branch name and branch description to every commit message.
#
NAME=$(git branch | grep '*' | sed 's/* //') 
DESCRIPTION=$(git config branch."$NAME".description)

echo "$NAME"': '$(cat "$1") > "$1"
if [ -n "$DESCRIPTION" ] 
then
   echo "" >> "$1"
   echo $DESCRIPTION >> "$1"
fi 

Creates following commit message:

[branch_name]: [original_message]

[branch_description]

I'm using issue number as branch_name, issue description is placed to the branch_description using git branch --edit-description [branch_name] command.

More about branch descriptions you can find on this Q&A.

The code example is stored in following Gist.

Use the prepare-commit-msg or commit-msg githook.

There are examples already in your PROJECT/.git/hooks/ directory.

As a security measure, you will have to manually enable such a hook on each repository you wish to use it. Though, you can commit the script and copy it on all clones into the .git/hooks/ directory.

A bit simpler script that adds the branch name to the commit message before you edit it. So if you want want to change or remove it you can.

Create this file .git/hooks/prepare-commit-msg:

#!/bin/bash

branchPath=$(git symbolic-ref -q HEAD) #Somthing like refs/heads/myBranchName
branchName=${branchPath##*/}      #Get text behind the last / of the branch path

firstLine=$(head -n1 $1)

if [ -z "$firstLine"  ] ;then #Check that this is not an amend by checking that the first line is empty
    sed -i "1s/^/$branchName: \n/" $1 #Insert branch name at the start of the commit message file
fi

You can do it with a combination of the prepare-commit-msg and pre-commit hooks.

.git/hooks/prepare-commit-msg

#!/bin/sh

BRANCH=`git branch | grep '^\*' | cut -b3-`
FILE=`cat "$1"`
echo "$BRANCH $FILE" > "$1"

.git/hooks/pre-commit

#!/bin/bash

find vendor -name ".git*" -type d | while read i
do
        if [ -d "$i" ]; then
                DIR=`dirname $i`
                rm -fR $i
                git rm -r --cached $DIR > /dev/null 2>&1
                git add $DIR > /dev/null 2>&1
        fi
done

Set permissions

sudo chmod 755 .git/hooks/prepare-commit-msg
sudo chmod 755 .git/hooks/pre-commit

add the below code in prepare-commit-msg file.

#!/bin/sh
#
# Automatically add branch name and branch description to every commit message except merge commit.
#

COMMIT_EDITMSG=$1

addBranchName() {
  NAME=$(git branch | grep '*' | sed 's/* //') 
  DESCRIPTION=$(git config branch."$NAME".description)
  echo "[$NAME]: $(cat $COMMIT_EDITMSG)" > $COMMIT_EDITMSG
  if [ -n "$DESCRIPTION" ] 
  then
     echo "" >> $COMMIT_EDITMSG
     echo $DESCRIPTION >> $COMMIT_EDITMSG
  fi 
}

MERGE=$(cat $COMMIT_EDITMSG|grep -i 'merge'|wc -l)

if [ $MERGE -eq 0 ] ; then
  addBranchName
fi

It will add branch name to commit message except merge-commit. The merge-commit has branch information by default so extra branch name is unnecessary and make the message ugly.