Git Exercise 1 - Start tracking files

Quick note: Git has extensive documentation. If you are unsure about any command or want to explore the many possible options, run git help <command> to get this information. (Scroll with arrow keys and exit with q.)

Create a directory to house your work

You and your friends need to plan some apartment work. Let’s start writing all those ideas down. Create a directory for this project:

At the terminal, type:

mkdir apartment
cd apartment

Start tracking changes

Now we can create a git repository inside this directory to track our work. This step can be done at any time but let’s see what happens in a very simple situation:

git init

Note: Git will give you a confirmation message that a repo has been created. Note that a hidden directory called .git has been created in your project directory. This contains the actual revision database (all snapshots are in there).

Now let’s add some tasks for the living room.

Note: We’ll be using a very basic text editor called nano.

Note thtat the Control key is used if you have a Mac as well

nano living_room.txt

Add some tasks to this file, e.g.

- paint
- move furniture

then save and close it.

How is this file handled by git? It isn’t yet! Take a look at the current status of the repo:

git status

Git tries to be helpful. It’s worth reading the messages it outputs. Sometimes they will tell you exactly what to do next.

Let’s add our new file:

git add living_room.txt

Look at the status again. You will see that the file is now marked for tracking. But right now, it’s only in the staging area as a “new” file.

To actually record its addition, we need to commit the contents of the staging area:

git commit -m "Start planning living room"

Notes:

-m stands for “message”. According to widespread practice, this should be short and in the imperative mood (i.e. “do thing” instead of “done thing”) to reflect project to-do items. It’s also not supposed to describe what has been done in detail, since that can be seen by inspecting the revision. Stating the context or purpose is preferred.

Git really wants you to write a commit message. So if you only write git commit, git will open a text editor in which you are to write a description of the commit. Here you can also enter a longer description. Just add a blank line after the message and write what you think is informative.

That’s it! Now the current state of the project is saved and you can always compare future states to this one or come back to it.

To get the list of all revisions, along with relevant information, run:

git log

If you only want the last K revisions, run

git log -n K

Sometimes output like this from git can be very long. Git will display (“pipe”) this text through a program that allows scrolling vertically through the whole output (using up / page up and down / page down keys). You will notice this happens since at the bottom of the screen you will see a : prompt, not the bash terminal. Press q to quit this scrollable display and return to the command line.

Note: The long alphanumeric code after the word “commit” is the unique identifier of the revision. After merging branches, simply saying “revision 1” and “revision 2” stops making sense since the history is no longer linear.

Take-aways

Further reading

Next

Exercise 2

Chalmers University of Technology 2018