A cheat sheet on Git commands

git_commands.md

A cheat sheet on Git commands introduced by Corey Schafer's Git Tutorials and some awesome blog posts.

Contents

• Basic commands
  • Defining user
    • Modifying exposed emails in previous commits in a batch-process way
    • Modifying email just in the last commit
  • Storing GitHub credentials in macOS keychain
  • Initializing git
  • Adding files to staging area
  • Removing files from staging area
  • Doing the first commit
  • Cloning a remote repo
  • Viewing info about remote repo
  • Pushing changes
• Common workflows
  • Adding a feature
  • Syncing a fork
• Commit message format
• How to fix mistakes
  • Fixing the last commit
    • Changing message
    • Adding files
  • Grabbing a commit from another branch
  • Removing a commit (reset)
    • Soft
    • Mixed
    • Hard
  • Undoing while preserving commit history
  • Discarding changes in the working directory
  • Getting rid of untracked files
  • Recovering deleted changes
  • A Comparison of reset, checkout, and revert
• How to stash
  • Saving the changes temporarily
  • Bringing back the changes
  • Deleting all stash
• How to rebase
  • Rebasing all feature commits on the tip of master
    • All at once
    • Step by step (with interactive rebase)
  • Force-Pushing
  • Interactive Rebase
    • Modifying the last 3 commits
    • Finding the sub-branch root and modifying the whole branch
    • Modifying fundamentally from the root commit
  • Rebasing all my shared-feature commits on the tip of the recently updated remote shared-feature
• Where to store .gitignore
• How to use git diff for notebooks

⇧

Basic commands

Defining user

git --version
git config --global user.name "first_name last_name"
git config --global user.email "some_number_github_offers+my_github_id@users.noreply.github.com"

git config --list

⇧

Modifying exposed emails in previous commits in a batch-process way

git filter-branch --env-filter '
WRONG_EMAIL="wrong@example.com"
NEW_NAME="New Name Value"
NEW_EMAIL="correct@example.com"

if [ "$GIT_COMMITTER_EMAIL" = "$WRONG_EMAIL" ]
then
    export GIT_COMMITTER_NAME="$NEW_NAME"
    export GIT_COMMITTER_EMAIL="$NEW_EMAIL"
fi
if [ "$GIT_AUTHOR_EMAIL" = "$WRONG_EMAIL" ]
then
    export GIT_AUTHOR_NAME="$NEW_NAME"
    export GIT_AUTHOR_EMAIL="$NEW_EMAIL"
fi
' --tag-name-filter cat -- --branches --tags

Resource: How can I change the author name / email of a commit? # Using git filter-branch

⇧

Modifying email just in the last commit

git commit --amend --author="first_name last_name <some_number_github_offers+my_github_id@users.noreply.github.com>"

⇧

Storing GitHub credentials in macOS keychain

git config --global credential.helper osxkeychain

"The next time you clone an HTTPS URL that requires authentication, Git will prompt you for your username and password. When Git prompts you for your password, enter your personal access token (PAT) instead. Once you've authenticated successfully, your credentials are stored in the macOS keychain and will be used every time."

Resource: Caching your GitHub credentials in Git

⇧

Initializing git

ls -la
git init
ls -la
git status
touch .gitignore

...adding ignored files...

git add .gitignore
git status

⇧

Adding files to staging area

git status
git add my_file
git add -A // all except ignored ones
git status

⇧

Removing files from staging area

git status
git reset my_file
git reset // all files
git status

⇧

Doing the first commit

git add -A
git commit -m "Initial Commit"
git status
git log

⇧

Cloning a remote repo

git clone ../remote_repo.git .
git clone https://github.com/my_github_id/remote_repo.git .

⇧

Viewing info about remote repo

git remote -v
git branch -a

⇧

Pushing changes

git diff
git status
git add -A
git commit -m "My new feature description"
git pull origin master
git push origin master

⇧

Common workflows

Adding a feature

1. Create a branch for desired feature:

git branch calc_divide
git checkout calc_divide

…writing code…

commit -m "Develop function calc_divide"

2. After commit, push branch to remote:

git push -u origin calc_divide
git branch -a

3. If other people also approved, merge branch:

git checkout master
git pull origin master
git branch --merged
git merge calc_divide
git branch --merged
git push origin master

4. Delete the merged branch:

git branch --merged
git branch -d calc_divide
git branch -a
git push origin --delete calc_divide

⇧

Syncing a fork

1. Configure an upstream for the local repo:

git remote -v
git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git
git remote -v

2. Sync the local repo with the upstream:

git fetch upstream
git checkout master

then either

git merge upstream/master

or

git rebase upstream/master

3. Push master from the updated local repo to origin at GitHub:

git push origin master

or

git push -f origin master

⇧

Commit message format

1. title (imperative mood) <= 50 chars
2. blank line
3. body, each line <= 72 chars, blank line between paragraphs
   • the reasons why you made the change in the first place
   • the way things worked before the change
   • what was wrong with that
   • the way they work now
   • why you decided to solve it the way you did
4. Resolves: #IssueNumber

⇧

How to fix mistakes

Fixing the last commit

Changing message

git commit --amend -m "New commit message"

It changes the commit hash, so the git history changes too. It’s good when commits are not yet shared with people. Otherwise, use git revert.

⇧

Adding files

git add my_missed_file
git commit --amend
git log --stat

Press :wq to save the commit message prompt and exit it.

⇧

Grabbing a commit from another branch

Let's grab the last commit from master to my-feature-branch:

git checkout master
git log

Copy a beginning piece of the hash belonging to the last commit:

git checkout my-feature-branch
git cherry-pick piece_of_hash

⇧

Removing a commit (reset)

Soft

It keeps our changes in the staging area.

git reset --soft piece_of_hash

⇧

Mixed

It keeps our changes in the files, but it doesn't add them to staging area.

git reset piece_of_hash

⇧

Hard

We get rid of all the changes after the commit!

git reset --hard piece_of_hash

⇧

Undoing while preserving commit history

It reverses the effects of some earlier commits via a new undoing commit. That way, it adds to the commit history; it neither modifies nor deletes it. Thus, it's a safe way of undoing the commits that have already been shared.

git log
git revert piece_of_hash
git log
git diff piece_of_hash piece_of_new_commit_hash 

⇧

Discarding changes in the working directory

git checkout -- .

or

git reset --hard

⇧

Getting rid of untracked files

It deletes all untracked directories and files!

git clean -df

⇧

Recovering deleted changes

It stores all commits even the lost ones for around 30 days in trash. It can be a life-saver!

git reflog

It shows commits in the order of when you last referenced them. Copy the hash of the commit that you wish to recover.

git checkout piece_of_hash 
git log
git branch restoring-branch
git checkout restoring-branch
git log

⇧

A Comparison of reset, checkout, and revert

Command	Scope	Common use cases
git reset	Commit-level	Discard commits in a private branch or throw away uncommitted changes
git reset	File-level	Unstage a file
git checkout	Commit-level	Switch between branches or inspect old snapshots
git checkout	File-level	Discard changes in the working directory
git revert	Commit-level	Undo commits in a public branch
git revert	File-level	(N/A)

Resource: Git Reset vs Revert vs Checkout reference

⇧

How to stash

Saving the changes temporarily

It allows us to switch branch without committing them.

git stash save "Worked on the functionality blah"
git stash list
git checkout other-branch

⇧

Bringing back the changes

git checkout bloh-branch
git stash list

Apply and then delete:

git stash apply stash@{some-id}
git stash drop stash@{some-id}

Apply and delete simultaneously:

git stash pop

⇧

Deleting all stash

It deletes current unsaved changes too!

git stash clear

⇧

How to rebase

The golden rule: rebase only your un-forked branches!

A comprehensive resource: Merging vs. Rebasing

⇧

Rebasing all feature commits on the tip of master

It results in a perfectly linear history :)

⇧

All at once

git checkout feature
git rebase master

⇧

Step by step (with interactive rebase)

git checkout feature
git rebase -i master

⇧

Force-Pushing

When the commit history on your remote repo is different from your rebased local one, you have to force-push your local changes to the remote—which irreversibly overwrites the remote history!

git checkout feature

# Be very careful with this command!
git push origin feature --force

⇧

Interactive Rebase

Modifying the last 3 commits

git rebase -i HEAD~3

⇧

Finding the sub-branch root and modifying the whole branch

git merge-base feature master
git rebase -i piece_of_hash

⇧

Modifying fundamentally from the root commit

git rebase -i --root

⇧

Rebasing all my shared-feature commits on the tip of the recently updated remote shared-feature

git checkout shared-feature
git pull origin shared-feature --rebase

Resource: How to Write a Git Commit Message

⇧

Where to store .gitignore

• Global (for cache files)

nano ~/.gitignore_global

• Local (for additional files that are specific to the project and that should be ignored on other computers too)

nano ./.gitignore

⇧

How to use git diff for notebooks

• Usual

git diff

• Graphical

nbdiff-web

Resource: Version control integration

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