Miscellaneous
Git

Git

Git is a version control system that is used to track changes in a file system. When present, it is possble to view the history of changes, revert to previous versions, and work on different versions of the same file.

Many tutorials and guides are available online, such as GitHub’s tutorial or the visual git guide.

Basic usage

  • git commit

    This command is used to save changes to the local repository.

    Here are some useful options:

    OptionDescription
    -m "message"Use the given message as the commit message.
    -aAutomatically stage files that have been modified and deleted.
    --date="Thu Jan 04 2024 13:33:37 GMT+0100"Use the given date as the commit date. This only sets the author date but not the commiter date

  • git commit --amend

    This command is used to modify the last commit. It opens the default text editor to modify the commit message. It is also possible to add or remove files from the commit.

    Here are some useful options:

    OptionDescription
    --no-editUse the previous commit message.
    --reset-authorUse the current user as the author of the commit.
    --date="Thu Jan 04 2024 13:33:37 GMT+0100"Use the given date as the commit date. This only sets the author date but not the commiter date

  • git reset <commit>

    Undoes all commits after the given commit, but keeps the changes in the working directory. Here are some useful options:

    OptionDescription
    --softKeep the changes in the staging area.
    --hardDiscard the changes in the staging area.

  • git log

    This command is used to view the history of the repository. Here are some useful options:

    OptionDescription
    --onelineShow each commit on a single line.
    --graphShow the commit history as a graph.
    --allShow the history of all branches.
    --since="3 days ago"Show commits since the given date.
    --author="name"Show commits by the given author.
    --grep="pattern"Show commits that match the given pattern.

Tricks

  • Change the commiter date to the author date

    Warning: This command rewrites the history of the repository. It should only be used on commits that have not been pushed to a remote repository.

    # On the current branch
git filter-branch --env-filter 'export GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"'

# On specific commits
git filter-branch --env-filter 'if [ $GIT_COMMIT = "commit_hash" ]; then export GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"; fi'

  • The HEAD pointer

    The HEAD pointer is a reference to the current commit. It is possible to move the HEAD pointer to a different commit using the git checkout command. This is useful to view the state of the repository at a specific commit.

    # Move the HEAD pointer to the given commit
git checkout commit_hash

    It is possible to reference the parent of the current commit using the ^ symbol. For example, HEAD^ references the parent of the current commit, and HEAD^^ references the grandparent of the current commit.