git

Free and open source distributed version control system.

Main Features

• Not a file delta‑based (difference) VCS
• Store a series of references of snapshots i.e stream of snapshots
• Integrity is verified by checksums i.e SHA‑1 used for checksum
• Stages
  • Modified = Working Directory
  • Staged = Staging Area
  • Committed = Repository
• Offline documentation can be accessed using man git or git help <COMMAND> or git <COMMAND> -h

First Time Setup / Config

git config maintains the configuration settings for all the repositories and users.

Scope	Command to View (git config)	Location	Remark
System	--system	/etc/gitconfig	All users and repos
Global	--global	~/.gitconfig or ~/.config/git/config	One user and all repos
Local	--local	.git/config	One user and one repo

# List the current used configs
git config --list --show-origin

# Set the user related configs
git config --global user.name "<YOUR_NAME>"
git config --global user.email "<YOUR_EMAIL>"

# Default Editor used by git
git config --global core.editor vim

# Specify default branch for the repos
git config --global init.defaultBranch main

# Getting single config
git config <CONFIG_KEY>
git config user.name

Basics

• Types
  • Tracked files (Committed + Staged files)
  • Untracked files
• Lifecycle
  • Untracked
  • Unmodified
  • Modified
  • Staged
• .gitignore file is used to specify untracked files
  • lines starting with # are comments and are ignored
  • lines starting with ! are skipped and not included in the untracked files

Add, clone, status, commit commands

git init   # Initialize an empty git repository

# To clone a existing repository
git clone <URL>
git clone <URL> <CUSTOM_DIRECTORY_NAME>   # Clone the repo in a user–defined directory

# Add files for tracking
git add <FILE_NAME/DIRECTORY_NAME>   # Recursively add the files

# Checking the status of the Tracked / Untracked files
git status
git status --short   or   git status -s   # Short status

# Committing the changes
git commit -m "COMMIT_MESSAGE"
git commit -a -m "COMMIT_MESSAGE"   # Staging and committing the changes in a single command

diff

# Checking the changes
git diff            # What changes but NOT staged
git diff --staged   # what changed between staged and the last committed files
git difftool        # GUI diff using the default GUI diff tool

log

# Checking the history and previous commits in reverse chronological order
git log
git log -p                   # Display history along with the diff changes for each commit
git log --stat               # Display history along with the changes count for each file
git log --pretty=oneline     # Display only commit messages
git log --oneline            # Display only commit messages
git log --graph              # Clean graph view from all the branches
git log -<n>                 # Top n commits to view
git log --since <CUSTOM_DATE_TIME>  # Only shows commits since the given datetime
git log --until <CUSTOM_DATE_TIME>  # Only shows commits until the given datetime
git log -S STRING_TO_TRACK         # Returns the commits in which the given STRING_TO_TRACK was changed/Updated/Added/Deleted

Basics ‑ II

Making additional changes to the last committed commit

git commit --amend            # Keeps the same commit message but adds the new staged files to the commit
git cherry‑pick <COMMIT_ID>   # Pick a specific commit and add it to current checked out branch

Remote Repository Management

git remote                # Lists all the remotes
git remote -v             # Lists the remotes along with the urls
git remote add <REMOTE_NAME> <REMOTE_URL>         # Add a separate remote
git remote add upstream <REMOTE_UPSTREAM_URL>    # Add an upstream
git remote show <REMOTE>                            # Show details of the changes between the remote and local
git remote remove <REMOTE>                         # Remove a remote from local
git remote rename <OLD_REMOTE_NAME> <NEW_REMOTE_NAME>

git fetch <REMOTE>                                 # Pulls the changes to the local from remote and DON'T Merge. Manual Merging required
git pull <REMOTE>                                  # Pulls the changes and merges to local as well
git pull <REMOTE_NAME> <BRANCH_NAME>               # Pulls a specific remote branch

git config --global pull.rebase "true"         # Rebases when merging

Tagging

• Types
  • Lightweight ‑ Pointer to specific commit
  • Annotated ‑ Explicitly stored in the commit object along with additional info like tag user name etc

git tags -l / --list               # List the tags existing
git show <TAG_NAME>                # Display a tag
git tag <TAG_NAME>                  # Create a lightweight tag
git tag <TAG_NAME> <COMMIT_HASH>   # Create a lightweight tag for an old commit
git tag -a v0.1.1 -m "<TAG_NAME>"  # Create an annotated tag

git push origin <TAG_NAME>         # By default, tags are not pushed to remote. Manually push

git tag -d <TAG_NAME>              # Delete a tag locally
git push origin --delete <TAG_NAME> # Delete a tag from remote

git checkout -b <NEW_BRANCH_NAME> <TAG_NAME>   # Creating a new Branch from a tag

Alias

git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.st status

Branching

• Stores a series of snapshots
• commits store pointers to commit objects

git branch <NEW_BRANCH>           # Only Creates a new branch, Doesn’t switch to that branch
git branch -d <BRANCH>            # Delete a branch

git checkout -b <NEW_BRANCH>      # Creates a new branch and switch to that branch
git checkout <BRANCH>              # Switches the HEAD pointer to that branch

git switch <BRANCH>                # Checkout this branch
git switch -c <NEW_BRANCH>         # Creates a new branch and switches to that branch.

Merging

• merges diverged code commits

git checkout <MASTER_BRANCH>        # Checkout to the branch to which you need to merge the branch changes
git merge <BRANCH_NAME>              # merges the BRANCH_NAME changes to the current checked out branch i.e MASTER_BRANCH

Stashing

• Save local changes without committing

git stash                           # saves local changes to stash
git stash list                      # show the stashed changes
git stash pop                       # load the last stashed changes into the working directory
git stash pop stash@{0}             # Pop a specific stash number instead of the latest one
git stash drop stash@{0}            # Drop a specific stashed changes