GIT cheat sheet | Alexandre Hublau

Here are my cheat sheet about most used GIT command !

All the commands below are picked from the official GIT documentation here https://git-scm.com/docs

Install git

For Windows: https://git-scm.com/download/win

For Linux: (usually it is installed by default)

apt install git # On Debian distros

Initialize git

First, we need to initialize git with some values

git config --global user.name "<firstname> <lastname>"
git config --global user.email "<email>"
git config --global core.editor "vim" # Or use "nano" if you prefer !
git config --global color.ui auto

Create an SSH key

To use git, you will have to create an SSH key:

# The command to generate an SSH key may change over the time ; please look on this github blog link :
ssh-keygen -t ed25519 -C "your_email@example.com"

See more information here: https://docs.github.com

Create a new GIT project

Into your root project directory

git init

Download an existing project

git clone <projet_url>
git clone <projet_url> <path_directory>
git clone <projet_url> --depth=1 # Clone only the last commit

Note: you can clone a project using HTTPS or SSH:

git clone https://github.com/torvalds/linux.git --depth=1
git clone git@github.com:torvalds/linux.git linux --depth=1

Basic git commands (add/commit/log…)

git status

git diff
git diff --staged
git diff --color-words # Diff line by line

Do modifications

git add <filename>
git add . # To add everything

# Unadd file
git reset <filename>

# Undo a file modification
git checkout <filename>
git checkout . # Undo for every file

git commit
git commit -m "<my message>"
git commit -am "<my_message>" # Commit modified or deleted files (not added files !)

# Modify last commit
git commit --amend

# Check the history
git log
git log --oneline
git log --graph --oneline --decorate

# Remove last commit
git reset --soft <commit_id> # Remove last commit but keep the modification
git reset --soft HEAD^
git reset --hard HEAD^ # Remove and clean last commit
# "HEAD" represents the last commit, "HEAD^" represents the commit before "HEAD"
# "HEAD^^" represents the commit before "HEAD^", etc...

git revert <commit_id> # Undo this commit

git diff
git diff <commit_id> <commit_id>

git diff <commit_id>^ <commit_id> # "^" means "current commit -1"
git diff <commit_id>^^ <commit_id> # "^^" means "current commit -2"
# etc...

git diff HEAD^ HEAD

Branches

A GIT branch is an independent copy of a project. Inside a branch, you can do tests before merging in the main or master branch.

git checkout -b <my_branch> # Create a new branch and go there
git branch -a # List the branches
git checkout <my_branch> # Change branch
git branch -d <my_branch> # Delete a (local) branch

git checkout - # Go to previous branch

# Merge/Rebase modifications from another branch in the current branch
git merge <my_branch>
git rebase <my_branch>

# Squash commits
git rebase <my_branch> --interactive

Push modification online

git remote add origin <git-repository-url>

git push -u origin <my_branch> # For the first time you push a branch
git push -u origin <my_local_branch>:<my_remote_branch>
git push

git push -f # Force push a branch

git fetch # Fetch the git information from the distant repository
git pull # = "git fetch && git merge"

To automatically exclude files from the working directory, you can create a .gitignore file (in the root directory, for example). The syntax of the file is simple:

/node_modules/
/vendor/
/public/
/.vscode/
/resources/
/.env

*.log
*~
a.out

Here, all these files will never be committed. Very useful to not commit files who contain passwords or API keys !

Stash the changes

git stash # Put your modifications in a stash
git stash pop # Pop your modification from the stash
git stash list
git stash drop
git stash clear

Find bugs

git bisect start # Find a commit who broke the application
git bisect bad
git bisect good <commit_id>

Aliases

We can define aliases like this :

git config --global alias.ac "commit -am"
git ac "commit !"

Hooks

Hooks are small scripts executed when an event is triggered in GIT.

Hooks can be created in the .git/hooks/ or $HOME/.git/hooks/ folder.

You can specify a custom GIT hook folder in your configuration (in $HOME/.gitconfig):

[core]
    hooksPath = /home/$HOME/git/hooks

The hook list is:

applypatch-msg
pre-commit
prepare-commit-msg
commit-msg
post-commit
post-checkout
pre-receive
update
post-update

If we want to add a commit convention to your GIT project, you can add a commit-msg hook in .git/hooks/commit-msg like:

#!/bin/bash

msg=`cat $1`

regex="^(revert: )?(feat|fix|polish|docs|style|refactor|perf|test|workflow|ci|chore|types|build)(\(.+\))?: .{1,50}"

if [[ ! $msg =~ $regex ]]; then
    echo "Regex does not match"
    echo "$regex"
    exit 1
fi

echo "$msg" > $1

Don’t forget to add permissions with this command:

chmod ug+x .git/hooks/*

An another use case would be to add emojis in your commit messages when a regex is typed with:

msg=`echo "$msg" | sed 's/🎉/🎉/'`
msg=`echo "$msg" | sed 's/:revert:/⏳/'`
msg=`echo "$msg" | sed 's/:build:/📦/'`
msg=`echo "$msg" | sed 's/:ci:/🤖/'`
msg=`echo "$msg" | sed 's/:docs:/📖/'`
msg=`echo "$msg" | sed 's/:feat:/🌟/'`
msg=`echo "$msg" | sed 's/:fix:/🚑/'`
msg=`echo "$msg" | sed 's/:perf:/⚡/'`
msg=`echo "$msg" | sed 's/:refactor:/🚧/'`
msg=`echo "$msg" | sed 's/:style:/💄/'`
msg=`echo "$msg" | sed 's/:test:/✅/'`

Clean GIT

git clean -df # Clean untracked files

git gc # Speed up the repository (it is made up automatically by git)

Cleaning up old remote git branches

Sometimes you may need to clean the branches in your local git repository.

# Example:

git branch -a

# * main
#   tmp/reorg
#   remotes/origin/HEAD -> origin/main
#   remotes/origin/main
#   remotes/origin/tmp/generateSummary
#   remotes/origin/tmp/lastModified
#   remotes/origin/tmp/reorg
#   remotes/origin/tmp/revealjs
#   remotes/origin/tmp/storybook
#   remotes/origin/tmp/useTranslation

# -----------------

git branch -r -d origin/<branch_name>

# or

git remote prune origin --dry-run
# you can remove --dry-run once you are sure about this action

# or

git fetch origin --prune --dry-run
# you can remove --dry-run once you are sure about this action

#
# Pruning origin
# URL: git@github.com:xandermann/<repo>.git
#  * [would prune] origin/tmp/generateSummary
#  * [would prune] origin/tmp/revealjs
#  * [would prune] origin/tmp/storybook
#  * [would prune] origin/tmp/useTranslation
#