Git

Introduction

Git is a distributed revision control system (VCS), designed to work well with highly non-linear workflows. It was initially conceived to support development of the Linux kernel, and has since become the most widely-used VCS for software development.

This page is essentially a cheat-sheet for git commands frequently used by our group.

If you're completely new to git or version control in general, Learn Git Branching is a great interactive, visual training program show the basics.

Basic Git

Basic information to get started with Git can be found at http://rogerdudler.github.io/git-guide/.

Git repository (repo)

Is a directory that contains files of the current branch and a hidden .git directory

Contains an Index in .git that acts as a staging area for all your branches

Contains a HEAD in .git that points to the last commit you made

Your PHASTA repository should always be at ~/git-phasta/phasta

Create a new repository

git init

Checkout a repository

git clone /path/to/repo

git clone user@host:/path/to/repo

Add files to be tracked in the git index

git add <filename1> <filename2> ...

git add *

git add -u (all files updated since last commit)

Commit changes to HEAD

git commit -m "my_username: my comments about this commit"

Push changes to remote repo

git push origin master (pushes the master branch to the original/main repo)

Connect to a remote server

git remote add origin <server> (connects <server> to your main, or origin repository)

git remote add myrepo <server> (connects <server> to a named branch called mybranch)

Note: <server> could be user@host:/path/to/repo

Create and delete branch

git checkout -b branch_name (creates and checkout branch)

git checkout master (checkout master branch)

git branch -d branch_name (delete branch we just created)

Push branch to a remote

git push origin branch (pushes from your main origin repo)

Update and merge

git pull (so all branches are up-to-date for the merge)

git merge origin/master (merges current branch with origin's master branch)

If a merge has conflicts, you need to edit the conflict files provided by Git, and then mark them as merged with git add

Compare code in different branches

git diff <branch_a> <branch_b>

View history of commits

git log

git log --author=foo

git log --pretty=oneline (show each commit as one line)

git log --graph --oneline --decorate --all (ASCII tree of branches, commits, merges)

git log --name-status (show which files changed in each commit)

git log --help (more information)

Git Prompt Statement (PS1)

1. Acquire git-prompt.sh from https://github.com/git/git/blob/master/contrib/completion/git-prompt.sh, and save it somewhere like ~/.git-prompt.sh
2. Edit your ~/.bashrc to say source ~/.git-prompt.sh before the lines that set your PS1
3. Modify your PS1 string to include $(__git_ps1 "(%s)") where you want the current branch to appear in your prompt