Using git for Source Control 101

Using git for source control has become ubiquitous with software development, and has largely replaced older source control methods, including CVS, and Subversion (SVN).  Here’s some of the more common git commands.

Initializing a Repository

Here are the basic commands to initialize from a new or existing repository.  Note, that the git add , git commit , and git push  commands are the most common commands that you will use, repeatedly, and in that order, when making changes to code that is under git source control.

# Git global setup
git config --global user.name "Jeff"
git config --global user.email "jeff@yourdomain.com"
# Create a new repository
git clone git@gitlabserver.yourdomain.com:GroupName/projectname.git
cd projectname
touch README.md
git add README.md
git commit -m "add README"
git push -u origin master
# Existing folder or Git repository
cd existing_folder
git init
git remote add origin git@gitlabserver.yourdomain.com:GroupName/projectname.git
git add .
git commit
git push -u origin master

Checking Status and Getting File Diffs

# show changes
git status
# show file diff of what has changed
git diff -- myfolder/mfile.cpp

Reverting, Resetting, and Cleaning – Be careful with these next commands!

# revert changes made in working copy
git checkout .
git checkout HEAD
# hard-reset of all un-pushed commits to master - WARNING: CARFUL WITH THESE ONE!!!
git reset
git reset --hard  # run git clean -fd after these
git reset --hard <commit_guid>
# revert to a specific commit
git revert <commit_guid_1> <commit_guid_2>
# remove untracked files (new, or generated, e.g., .DS_store)
git clean -f
# add -n for a preview of what will be removed
git clean -fdn
# actually, remove untracked files and directories, not just a preview
git clean -fd

Real-World Usage:

git reset --hard
git clean -fd
git checkout HEAD

Stashing, instead of Resetting

Instead of resetting, you can accomplish the same with git stash , and even use the changes later if you change your mind.

# basic stashing
git stash
git stash --all # removes all files and dirs from working copy
# using it later, if you changed your mind
git stash apply
# or simply remove the stashed changes with
git stash pop
# removes latest stashed state w/out applying to working copy
git stash drop