This is a test repository for the CS 368 Git/GitHub session. To clone this repo, run:
$ git clone [email protected]:varuncnaik/gitsession-sp17.git
These are the commands we ran during the session. Feel free to run them yourself to create a new local repo, and push it to GitHub. I have added some comments for clarity.
Firstly, we create a local repository ("local repo" for short):
$ mkdir <reponame>/
$ cd <reponame>/
$ git init
$ git status
Next, we create our first commit:
$ vim hello.cpp
$ g++ -std=c++11 hello.cpp
$ ./a.out
$ rm a.out
$ git commit -m "Initial commit" # Oops
$ git add hello.cpp
$ git status
$ git commit -m "Initial commit" # Success!
$ git status
$ git log
Then, we create our second commit:
$ vim hello.cpp
$ g++ -std=c++11 hello.cpp
$ ./a.out
$ git status
$ git diff
$ git add hello.cpp
$ git status
$ git diff # Oops
$ git diff --staged # Success!
$ git commit -m "Changed output message"
$ git status
$ git log
We want to push these local commits to a remote repository ("remote repo"). If we create an empty remote repo on GitHub, it will tell us to perform the following commands:
$ git remote add origin [email protected]:<username>/<reponame>.git
$ git push origin master
Now, we can copy our code (and history) on a new machine (or even to a different location on the same machine). We create a commit on the new machine and push it to GitHub:
$ git clone [email protected]:<username>/<reponame>.git
$ cd <reponame>/
$ git status
$ git log
$ vim README.md
$ git status
$ git add README.md
$ git diff --staged
$ git commit -m "Added README"
$ git push origin master
We pull our changes onto the original machine:
$ git pull origin master
$ git log
Suppose we use git add to add a file, but we do not want the file to be
included in the next commit. We can unstage the file:
$ git add a.out # Oops
$ git status
$ git reset HEAD -- a.out # Fixed
$ git status
If we want to remove the entire previous commit, we can run the following:
$ git add a.out # Oops
$ git commit -m "Bad commit" # Double oops
$ git log
$ git reset HEAD~1 # Fixed!
$ git log
If you are working on a project alone or in a small group, it is okay for
everyone to push to the master branch. But for large groups, you may want each
member to push changes to a topic branch, and merge the topic branch into the
master branch when they are finished. Such topic branches are usually named
username-description. Over the lifetime of the project, each user will
probably create multiple topic branches, where each branch contains several
related changes.
During the discussion session, I was the only user writing code, but I was
pushing commits from two machines. So, in the example below, I write lab and
macbook in the branch names instead of two usernames.
On the first machine (lab), we create a branch, perform a commit, and push
the branch:
$ git log
$ git branch
$ git checkout -b lab-helper-function
$ git branch
$ git status
$ vim hello.cpp
$ g++ -std=c++11 hello.cpp
$ ./a.out
$ git status
$ git add hello.cpp
$ git diff --staged
$ git commit -m "Created helper function"
$ git push origin lab-helper-function
On the second machine (macbook), we do something similar:
$ git log
$ git branch
$ git checkout -b macbook-interactive-prompt
$ git branch
$ git status
$ vim hello.cpp
$ g++ -std=c++11 hello.cpp
$ ./a.out
$ git status
$ git add hello.cpp
$ git diff --staged
$ git commit -m "Interactive prompt for name"
$ git push origin macbook-interactive-prompt
Now, we look at the state of the different branches on each machine, and also
on GitHub. The local repository on the lab machine has two branches master
and lab-helper-function. The local repository on the macbook machine has two
branches master and macbook-interactive-prompt. The remote repository on GitHub
has all three branches master, lab-helper-function, and
macbook-interactive-prompt.
On the lab machine, we merge the lab-helper-function branch into master, and
then push the updated master branch:
$ git log
$ git branch
$ git checkout master
$ git pull origin master # Nothing to pull
$ git branch
$ git merge lab-helper-function
$ git status
$ git log
$ git push origin master
On the macbook machine, we merge the macbook-interactive-prompt branch into
master. We have to resolve a merge conflict. Then, we push the updated master
branch:
$ git log
$ git branch
$ git checkout master
$ git pull origin master # Pull changes
$ git branch
$ git merge macbook-interactive-prompt
$ git status
$ vim hello.cpp # Fix merge conflict
$ g++ -std=c++11 hello.cpp
$ ./a.out
$ git status
$ git add hello.cpp
$ git status
$ git commit
$ git log
$ git push origin master
See the history of this repo for previous versions of the Makefile.
To learn more about git, see https://git-scm.com/book/en/v2