Basic commands

git init

Initialize new git repository in the current directory. This command will create .git directory that contains files related to the git repository.

cd repository_path
git init

git add

git add source.c log.txt

git add .  # every files except file name is starting with dot.

git add *.c  # files ending with '.c'

At some point, user will want to make record for current state of the repository.

Differences between previous commit and current state such as new, modified, deleted files are called untracked files.

git add command stages selected untracked files. Staged files can be unstaged. Use git status to show unstage command.

You may need to create .gitignore file to prevent specific files(automatically generated files, large files, etc.) being automatically staged.

  • .gitignore example
a.out
# ignore generated executable file

*.root
# ignore data file

*/**
# exclude child directories and files.

This .gitignore example is suitable for managing only source code in the current directory.

git status

Print staged files and untracked files and other useful information such as current branch name and unstage command.

git commit

Commit staged files. This will create a save point that reflects changed state of the repository.

A commit log includes commit hash, author, date and comment. You can change branch to other commit by using git checkout COMMIT_HASH command.

git log

List commit logs. There are various options for formatting, ordering, graphical branch representation, etc.

  • git log --oneline example
...

52b1cef Update README.md

...

52b1cef is short version of commit hash and following “Update …” is comment.

git checkout

Change current branch to other branch.

git checkout 52b1cef   # change to other commit by using commit hash

git checkout main  # change to main branch

Connect Git repository to remote repository

git remote add origin ADDRESS

Add remote repository and label it origin.

If you are using GitHub, ADDRESS can be either web URL or SSH key. Using URL dose not allow modifying the repository directly. Use SSH key If you want to modify the repository without pull request.

git push origin main

Update main branch of remote repository labeled origin using local repository.

git pull

Update local repository using remote repository.

  • If one or more untracked file is subject to change by an update, the update will not proceed. Users must commit or restore those files.
  • If local and remote repository cannot be merged automatically by git, user need to resolve the merge conflict.