"Force" pull a remote branch to a local

Sometimes you may commit to a branch (like main) by accident. Often the solution is to reset the a branch to the state of that branch on the remote repository. To do this, run the following:

git reset --hard origin/branch

Unstage an erroneously staged file

When running git add, sometimes files get staged that we may not want to stage. To unstage these files, run:

git reset ./path/to/file/you/wish/to/unstage.txt

Revert changes on an unstaged file

If you have made changes to an unstaged file you wish to revert, run the following:

git checkout ./path/to/file/you/wish/to/revert.txt

Combined unrelated git repos

How to combine two separate unrelated Git repositories into one with single history timeline:

git merge remote-name branch-name --allow-unrelated-histories

Get current commit's SHA1

Getting a specific commit's SHA1 value can be useful for hyperlinking on GitHub (and other things).

git rev-parse HEAD

Make a dummy commit

These dummy commits are useful for testing CI/CD and other integrations.

git commit --allow-empty

Create a zip archive for a specific branch

git archive --format zip --output filename.zip master

Git tag examples

The following are useful git tag examples:

# Show all released versions
git tag

# Show all released versions with comments
git tag -l -n1

# Create release version
git tag v1.0.0

# Create release version with comment
git tag -a v1.0.0 -m 'Message'

# Checkout a specific release version
git checkout v1.0.0

Git log examples

The following are some useful git log flags:

# Show one-line summary of commits
git log --oneline
git log --oneline -3 # show last 3

# Show only custom commits
git log --author="Steven"
git log --grep="Message"
git log --until=2020-01-01
git log --since=2020-01-01

# Show different summaries/stats
git log --stat --summary
git log --graph
git log --oneline --graph --all --decorate

Git diff examples

The following are some useful git diff flags:

# Compare modified files and highlight changes only
git diff --color-words index.html`

# Compare modified files within the staging area
git diff --staged

# Compare branches
git diff master..branchname
git diff --color-words master..branchname^

# Compare commits
git diff 6eb715d
git diff 6eb715d..HEAD
git diff 6eb715d..537a09f

# Compare commits of file
git diff 6eb715d index.html
git diff 6eb715d..537a09f index.html

# Compare without caring about spaces
git diff -b 6eb715d..HEAD
git diff --ignore-space-change 6eb715d..HEAD

# Compare without caring about all spaces
git diff -w 6eb715d..HEAD
git diff --ignore-all-space 6eb715d..HEAD

# Useful comparings
git diff --stat --summary 6eb715d..HEAD

# Blame
git blame -L10,+1 index.html

Split multiple subdirectories into a new git repo

Originally from: https://stackoverflow.com/questions/2982055/detach-many-subdirectories-into-a-new-separate-git-repository

This will remove all tags as well:

git filter-branch --tag-name-filter cat --index-filter 'git rm --cached -qr --ignore-unmatch -- . && git reset -q $GIT_COMMIT -- src/extractcode tests/extractcode' --prune-empty -- --all

After the above operation is finished, you will now have a repository that contains just the files + their commits that you specified above (src/extractcode and tests/extractcode). However, the git history will contain many empty merge commits from everything that was outside of the subset filtered above. To remove these empty merge commits, run the following:

git filter-branch -f --prune-empty --parent-filter \
'sed "s/-p //g" | xargs -r git show-branch --independent | sed "s/\</-p /g"'

At this point, your repo will now contain the specified files + directories you pulled out from and their git history. The final step is set the git remote for your "newly" created repository and push the changes there:

git remote set-url origin new-remote-url-here
git push -u origin branch-name

To prevent pushing to the source git repository, it may be a good idea to remove the old remote url:

git remote rm old-remote-name