My Git learning notes.

How to change most recent commit message#

After we have added a local commit, we may find that we need to do some updates before pushing to remote repo. We can use git commit --amend to change last commit.

With --amend option, we can change not just commit message. Files in local repo can also be updated. After using this option, last local commit will be replaced with the new commit.

References#

• https://stackoverflow.com/q/179123/6064933
• https://help.github.com/en/github/committing-changes-to-your-project/changing-a-commit-message

How to show changes for a specific file#

Sometimes, we want to show the changes for a particular file across commits. This can be achieved by git log command:

git log -p <file_path>

The -p option will show detailed diff info for the file.

A more complete and useful version is:

git log --stat -p --follow <file_path>

Meaning of options used:

• --stat: show info about file changed, deletions and insertions.
• --follow: show file change info before it was renamed (by default, file history before renaming is not shown).

To show only the latest five changes, we can use the -n option:

git log --stat -p --follow -n 5 <file_path>

A similar command is git whatchanged:

git whatchanged -p <file_path>

The git-whatchanged command is similar to git log and is kept for backward compatibility. New users are encouraged to use git log instead.

References#

• Difference between git-log and git-whatchanged.
• git-whatchanged doc.
• https://stackoverflow.com/a/12359963/6064933
• See changes to a specific file.
• https://kgrz.io/use-git-log-follow-for-file-history.html
• Git log doc.

How to set up editor for git commit#

I am used to writing my commit message on the command line with -m option (git commit -m "xxx"). This works well for short commit message. When we want to write the detailed explanation for a change in commit message, it is better to do it in a text editor, e.g., in Vim or Neovim.

There are basically two way to set up the editor.

• Set up the EDITOR and VISUAL env variable:

  export EDITOR="nvim"
  export VISUAL="$EDITOR"

• Set up the editor git uses via git config:

  git config --global core.editor "nvim"

After that, when you want to commit, just type git commit in the command line.

Neovim will be opened with a file named COMMIT_EDITMSG, you can edit this file. Anything not starting with # will be treated as your commit message. After you have done writing the commit message, exit the insert mode, save the file and quilt. This commit will be done.

References#

• https://stackoverflow.com/q/2596805/6064933
• https://stackoverflow.com/q/13239368/6064933