Git 2: Initial Setup
First-Time Setup
Refer to the Git book to install Git, then let’s get started! According to this page:
Now that you have Git on your system, you’ll want to do a few things to customize your Git environment. You should have to do these things only once on any given computer; they’ll stick around between upgrades. You can also change them at any time by running through the commands again.
Git comes with a tool called git config that lets you get and set configuration variables that control all aspects of how Git looks and operates.
The first thing you should do when you install Git is to set your user name and email address. This is important because every Git commit uses this information, and it’s immutably baked into the commits you start creating:
git config --global user.name "John Doe" git config --global user.email johndoe@example.com
Again, you need to do this only once if you pass the --global option, because then Git will always use that information for anything you do on that system. If you want to override this with a different name or email address for specific projects, you can run the command without the --global option when you’re inside that project’s working directory.
You can configure the default text editor that will be used when Git needs you to type in a message. If not configured, Git uses your system’s default editor.
git config --global core.editor vim
If at any time you wish to check your configuration settings enter:
git config --list
You may see keys more than once, because Git reads the same key from different files ([path]/etc/gitconfig and ~/.gitconfig, for example). In this case, Git uses the last value for each unique key it sees.
The Three Operations
Recall from the previous post there are 3 major Git operations: modifying, staging, and committing.
Working tree, staging area, and .git directory
I will proceed to take you through a concrete example of all three operations.
Modifying
To start, select any directory — say, for example, “project1” — and enter at the prompt:
mkdir project1
cd project1
git init
This creates an initial version of our repository — meaning a new subdirectory is created named .git inside the project1 directory that contains all of your necessary repository files — a Git repository skeleton. At this point, nothing in your project is tracked yet. See Git Internals for more information about exactly what files are contained in the .git directory you just created.
Now add a file to your project1 directory and the edit it with your favorite editor. Mine is gvim but there are many others. Editors are outside the scope of this document, but I do touch on them in a the FAQs. Refer to your individual editor’s documentation
touch proj1.py
chmod 775 proj1.py
What this does is:
create a file called proj1.py
chmod the file with the appropriate permissions
Add the following to proj1.py:
print(“Hello World”)
Then at the prompt enter:
python proj1.py
Which should output:
Hello World
Now we are ready to move on to staging.
Staging
Enter (at the prompt):
git status
It should output something like the following:
On branch master
No commits yet
Untracked files:
(use "git add <file>..." to include in what will be committed)
proj1.pynothing added to commit but untracked files present (use "git add" to track)
This tells us that
We are on the master branch
There are no commits yet
We have 1 untracked file that needs to be staged
Suggests we use git add to start tracking the file
Let’s do what git suggests and stage the file with
git add proj1.py
Now git status should yield:
On branch master
No commits yet
Changes to be committed:
(use "git rm --cached <file>..." to unstage)
new file: proj1.py
We have successfully staged the file and are ready to commit!
Committing
Enter at the prompt:
git commit -m "Added Hello World file."
-m is an optional argument that tells git not to open the default editor when executing the commit. If you did everything correctly up till now you should see:
[master (root-commit) 338caa5] Added Hello World file.
1 file changed, 1 insertion(+)
create mode 100755 proj1.py
Now the SHA 338caa5 will be different, and that’s as it should be. This is Git telling us:
the commit message
files changed and inserted
Git created a regular exectable file (see stackoverflow)
If we type git status now we should get:
On branch master
nothing to commit, working tree clean
Bravo! You have just done your first Git commit!
Best Practices
Only One Module Per commit
Consider making 1 commit per module as here.
ArduPilot generally employs a 1 commit per module approach.
The modules in the above example are:
Tools/autotest
Copter
AP_Baro library
hwdef
AP_HAL library
and so on…
Make Commit Messages Descriptive
Add Binary Files To .gitignore
See here.
Credits
https://linuxfromanoobie.wordpress.com/2018/04/15/git-starting-off/
https://opensource.com/article/20/7/git-best-practices
https://deepsource.io/blog/git-best-practices/
Next Installment
Next time we’ll take a look at collaboration via GitHub.
