3.2.4 Commits

Understanding commits

Technically, a commit is a single point in the history of a branch, but most developers use the term to mean a commit object, which stores information about a particular revision. A single commit can record changes to multiple source files, and typically represents one logical set of related changes (such as a bug-fix). You can list the ten most recent commits in your current branch with this command:

git log -10 --oneline

If you’re using an older version of Git and get an ‘unrecognized argument’ error, use this instead:

git log -10 --pretty=oneline --abbrev-commit

More interactive lists of the commits on the remote master branch are available at http://git.sv.gnu.org/gitweb/?p=lilypond.git;a=shortlog and http://git.sv.gnu.org/cgit/lilypond.git/log/.

How to make a commit

Once you have modified some source files in your working directory, you can make a commit with the following procedure:

  1. Make sure you’ve configured Git properly (see Configuring Git). Check that your changes meet the requirements described in Code style and/or Documentation policy. For advanced edits, you may also want to verify that the changes don’t break the compilation process.
  2. Run the following command:
    git status

    to make sure you’re on the right branch, and to see which files have been modified, added or removed, etc. You may need to tell Git about any files you’ve added by running one of these:

    git add file  # add untracked file individually
    git add .     # add all untracked files in current directory

    After git add, run git status again to make sure you got everything. You may also need to modify ‘GNUmakefile’.

  3. Preview the changes about to be committed (to make sure everything looks right) with:
    git diff HEAD

    The HEAD argument refers to the most recent commit on the currently checked-out branch.

  4. Generate the commit with:
    git commit -a

    The ‘-a’ is short for ‘--all’ which includes modified and deleted files, but only those newly created files that have previously been added.

Commit messages

When you run the git commit -a command, Git automatically opens the default text editor so you can enter a commit message. If you find yourself in a foreign editing environment, you’re probably in vi or vim. If you want to switch to an editor you’re more familiar with, quit by typing :q! and pressing <Enter>. See Configuring Git for instructions on changing the default editor.

In any case, Git will open a text file for your commit message that looks like this:

# Please enter the commit message for your changes.  Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#	modified:   working.itexi

Your commit message should begin with a one-line summary describing the change (no more than 50 characters long), and if necessary a blank line followed by several lines giving the details:

Doc: add Baerenreiter and Henle solo cello suites

Added comparison of solo cello suite engravings to new essay with
high-res images, fixed cropping on Finale example.

Commit messages often start with a short prefix describing the general location of the changes.

Visit the links listed in Understanding commits for examples.

LilyPond — Contributor’s Guide v2.21.6 (development-branch).