Git

Between ROOT Trees, Git Branches and Random Forest classifiers, I miss becoming a park ranger.

Git is a version control software, used currently for all programming projects. All information about Git can be inferred at this free book:

Git - Book

Therefore, here I will just report some notes on the commands I use more frequently:

Cloning a repository

Simply use

git clone repolink

it will create a folder with the same name of the repository (you can add a different name as second argument if you wish)

Commit changes

Check differences

It is a good practice to have a check of our changes, before committing them. We can do it with

git diff

or better (GUI-based)

git difftool

(I usually choose "meld" as difftool software, but it is a matter of taste)

For jupyter notebooks:

git difftool --tool=nbdime

Add files and performing commit

When you are ready to commit your changes, just do:

git add filename

git commit -m 'commit message'

Multiple files can be added in the same commit. It is often useful to group the files related to the same change.

Pushing changes to repository

Until you push them to an online repository (GitHub, GitLab...) they will be only in your local computer.

Always first pull your repository (even if you think there are no changes, it does not hurt to check)

git pull

Then you can launch the push

git push

If you get security errors, such as:

Permission denied (publickey). fatal: Could not read from remote repository.

Please make sure you have the correct access rights and the repository exists

You probably need to set a SSH keys on your github account (from settings).

Create ssh key according to the guide https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent, and activate it on your machine. Then copy the line from the file into the github account page

Branches

branches are quite complicated to use, so it is better to refer to the guide for details. But in general I need to create my branch

git checkout -b newbranch

move to an existing branch

git checkout mybranch

and merge (or rebase, with only difference the chronology of changes) some branches with each other

git merge other branch

Finally, I need to delete branches I do not use anymore:

git branch -d oldbranch

Rebase

Rebase it is similar to merge, but it applies your commits over the source commits. It may be recommended if you want the commit history to be more clear.

So you can git rebase origin/master to apply your commits over them :)

For more information: https://git-scm.com/docs/git-rebase

Cherry picking

Git command cherry-pick allows to apply only one commit to the code. The commit can come from whichever branch, and it can be identified with git log.

Example:

git cherry-pick 02e641bd62b6efe1924eb008413f2e57f4e9a996

Be careful that this does not cause conflict with your master branch