Copy the script in to a file post-commit and copy the file into the directory .git/hooks/ of your git project and make it executable.

You can change the name of the generated CHANGELOG file inside the post-commit file by modifying the variable OUTPUT_FILE to whatever you want. Some projects also use HISTORY.md, NEWS.md or RELEASE.md, but I suggest you stick to the convention.

The default setting of the script generates markdown, which can be seen in the CHANGELOG.md.

If you want to change the output format, you should read the Git documentation for pretty-formats and change the –formatargument in post-commit file according to your desired format.

You can test your output format by executing the following command inside your git repository folder:

git --no-pager log --no-merges --format="YOUR_FORMAT_GOES_HERE"

If you are happy with the result, just replace the command in the post-commit file with your command. Don't forget to pipe the output in you're CHANGELOG with > $OUTPUT_FILE at the end of the line.

The script uses Git Hooks to execute the git log command after every commit and write the output inside the CHANGELOG.md file.

Since we want to add the changes in our CHANGELOG.md as well, we have to use Git's --amend feature to change the previous commit and apply the changes from the script, too.

By changing the last commit, we are triggering the post-commit hook another time, since the –ammend commit is a commit as well. To prevent an infite execution of this hook, we have to check, whether our generated CHANGELOG.md have have changed at all. If it is executed the second time, the file should not be different.

We can check this by using the git status command with --porcelain and parse the output for our $OUTPUT_FILE. If the process returns a code higher than zero, we had a match and know that we have a changed CHANGELOG.md, which we have to append to our previous commit.

#!/bin/bash
set -eu
 
# destination of the final changelog file
OUTPUT_FILE=CHANGELOG.md
 
# generate the changelog
git --no-pager log --no-merges --format="### %s%d%n>%aD%n%n>Author: %aN (%aE)%n%n>Commiter: %cN (%cE)%n%n%b%n%N%n" > $OUTPUT_FILE
 
# prevent recursion!
# since a 'commit --amend' will trigger the post-commit script again
# we have to check if the changelog file has changed or not
res=$(git status --porcelain | grep -c ".\$OUTPUT_FILE$")
if [ "$res" -gt 0 ]; then
  git add $OUTPUT_FILE
  git commit --amend
  echo "Populated Changelog in $OUTPUT_FILE"
fi

Alle commits seit dem letzten Tag und ohne merges

git --no-pager log $(git describe --tags --abbrev=0)..HEAD --no-merges --format="### %s%d%n>%aD%n%n>Author: %aN (%aE)%n%n>Commiter: %cN (%cE)%n%n%b%n%N%n" > $OUTPUT_FILE