git

GIT

Setting up repositories

• git config command is used to customize Git behavior with:
  • --global for user-wide settings.
  • --local for repository-specific settings.
  • --system (admin access) for system-wide settings.
• git config --list: Displays the current Git configuration.
• For connecting to remote repo:
  • git config --global user.name "Your Name".
  • git config --global user.email "you@example.com".
  • Two ways to connect:
    • git clone <repository_url>: Downloads an existing repo.
      • Once changes are pushed, credentials (e.g., GitHub access tokens) are requested.
      • git clone -b <branch_name> --single-branch <repository_url>: Clones a branch.
      • git clone --recurse-submodules <repository_url>: Clones all submodules (other repositories inside it).
    • git init: Initializes a repo locally in the current dir, by creating .git dir, allowing tracking files. Then:
      • git init <directory_name>: Initializes in a dir.
      • git remote add <remote repo alias like origin> <remote_url>: Adds a remote repository.
      • git remote rm origin: Removes the repo.
      • git remote -v: Verifies it is added.
      • Exclude files or dirs from being tracked as specified in .gitignore eg.1.

Synching

• git status: Shows the status of changes in the working directory.
• git add .: Stages all changes for commit.
• git commit -m "message": Commits staged changes with a descriptive message.
• git commit --amend --no-edit: Adds currently staged changes to the last commit (with no message change)
• git show: Shows the last commit (metadata + diff).
• git pull origin <branch_name>: Fetches and merges changes from the remote branch.
• git push origin <branch_name>: Pushes local changes to the remote branch.
• git push -u origin main:
  • Sets the upstream branch, i.e., link the local branch to origin/main.
  • After git push and git pull alone possible.

Path shortcuts

• . : Current directory: (E.g., git status .: Status limited to current directory).
• .. : Parent directory: (E.g., git add ..: Stage changes from parent directory).
• ../.. : Two levels up (E.g., git diff ../..).
• -- : Separator between revisions and paths
  • Prevents ambiguity between branch names and file names.
  • E.g., git checkout -- file.txt: Restore file (not a branch named file.txt)
  • E.g., git log -- src/: History only for src/

Pathspec magic

• git add '*.py': All Python files.
• git add :/pattern: Search from repo root.
• git add :(exclude)tests/: Exclude path.
• git add src/ :(exclude)src/tmp/

Adding/removing

• git clean -f: Removes untracked files.
• git clean -fd: Removes untracked files and directories.
• git rm <file>: Removes a file from both the working directory and Git.
• git rm -r <dir>: Removes directory from git + disk.
• git blame <file>: Shows who changed which line (and when).
• git grep "pattern": Searches in tracked files (fast).
• git rm --cached .: Removes all from Git (used especially when we forget to add a file set in .gitignore).

Branching

• git branch -a: Lists all branches in the repository.
  • git branch: Lists local branches.
  • git branch -r: Lists remote branches.
• git branch <branch_name>: Creates a new branch.
• git branch -d <branch_name>: Deletes a branch.
• git branch -D <branch_name>: Force-deletes a branch.
• git remote -v: Lists remote repositories.
  • git remote -v: More verbose as it also
• git checkout <branch_name> or git switch <branch_name>: Switches to a branch.
  • git checkout -b <branch_name>: Creates and switches to a branch.

Merging

• git merge <branch_name>: Merges the specified branch into the current branch.
• git rebase <branch_name>: Reapplies commits on top of another branch (more linear than merging).
• git rebase -i <base>: Interactively rewrite commit history starting from eg.3.

Revision shortcuts

• HEAD: Current commit.
• HEAD~1: Parent of current commit.
  • E.g., git diff HEAD~1
  • E.g., git reset --hard HEAD~1
• HEAD~2: Two commits before HEAD.
• HEAD^: First parent (important in merges).
• HEAD^2: Second parent of a merge commit.
• @: Alias for HEAD (same thing).

Range notation

• Double dot A..B: Commits in B that are NOT in A.
  • E.g., git log --oneline --decorate --graph HEAD~5..HEAD
  • Used to see what will be merged.
• Triple dot A...B: Commits reachable from either A or B but not both.
  • E.g., git diff origin/main...HEAD
  • Used understand how far branches diverged.

Undoing Changes

• git checkout -- <file>: Reverts changes to a specific file (unstaged changes).
• git reset <file>: Unstages a staged file.
• git reset --soft HEAD~1: Removes the last commit but keeps changes staged.
• git reset --hard HEAD~1: Removes the last commit and discards changes.
• git revert <commit_hash>: Reverts changes made by a specific commit (creates a new commit).

Viewing History

• git log: Displays the commit history.
• git log --oneline: Shows a condensed commit history.
• git diff: Shows differences between working directory and staging area.
• git diff <branch_name>: Compares the current branch with another branch.
• git restore -p <file>: Shows or discards changes piece by piece: eg2.

Diff with ranges

• git diff A..B: Changes from A → B.
• git diff A...B: Changes from merge-base → B.
• git diff HEAD -- file.py: Diff file vs last commit.
• git diff --cached: Staged vs last commit.

Stashing

• git stash: Temporarily saves changes.
• git stash push -m "Work in progress on feature X": Stash with a comment.
• git stash --keep-index: Stash only the changes that are not staged for commit
• git stash list: Lists stashed changes.
• git stash apply: Applies stashed changes without removing them from stash.
• git stash apply stash@{1} Apply a specific stash.
• git stash pop: Applies and removes stashed changes.
• git stash clear: Clear them all.

Tagging

• git tag: Lists all tags.
• git tag <tag_name>: Creates a new tag.
• git push origin <tag_name>: Pushes a tag to the remote repository.

Collaboration

• git fetch: Fetches updates from the remote repository without merging.
• git cherry-pick <commit_hash>: Applies a specific commit to the current branch.