Creating a Repository
OverviewTeaching: 10 min
Exercises: 0 minQuestions
Where does Git store information?Objectives
Create a local Git repository.
Once Git is configured, we can start using it.
We will pretend we’re working with a team who are investigating if it is possible to send a planetary lander to Mars.
First, let’s create a directory in
Desktop folder for our work and then move into that directory:
$ cd ~/Desktop $ mkdir planets $ cd planets
Then we tell Git to make
planets a repository—a place where
Git can store versions of our files:
$ git init
It is important to note that
git init will create a repository that
includes subdirectories and their files—there is no need to create
separate repositories nested within the
planets repository, whether
subdirectories are present from the beginning or added later. Also, note
that the creation of the
planets directory and its initialization as a
repository are completely separate processes.
If we use
ls to show the directory’s contents,
it appears that nothing has changed:
But if we add the
-a flag to show everything,
we can see that Git has created a hidden directory within
$ ls -a
. .. .git
Git uses this special sub-directory to store all the information about the project,
including all files and sub-directories located within the project’s directory.
If we ever delete the
we will lose the project’s history.
We can check that everything is set up correctly by asking Git to tell us the status of our project:
$ git status
# On branch master # # Initial commit # nothing to commit (create/copy files and use "git add" to track)
If you are using a different version of
git, the exact
wording of the output might be slightly different.
Places to Create Git Repositories
Along with tracking information about planets (the project we have already created), Margaret would also like to track information about moons. Despite Juan’s concerns, Margaret Hamilton creates a
moonsproject inside her
planetsproject with the following sequence of commands:
$ cd ~/Desktop # return to Desktop directory $ cd planets # go into planets directory, which is already a Git repository $ ls -a # ensure the .git sub-directory is still present in the planets directory $ mkdir moons # make a sub-directory planets/moons $ cd moons # go into moons sub-directory $ git init # make the moons sub-directory a Git repository $ ls -a # ensure the .git sub-directory is present indicating we have created a new Git repository
git initcommand, run inside the
moonssub-directory, required for tracking files stored in the
No. Margaret does not need to make the
moonssub-directory a Git repository because the
planetsrepository will track all files, sub-directories, and sub-directory files under the
planetsdirectory. Thus, in order to track all information about moons, Margaret only needed to add the
moonssub-directory to the
Additionally, Git repositories can interfere with each other if they are “nested”: the outer repository will try to version-control the inner repository. Therefore, it’s best to create each new Git repository in a separate directory. To be sure that there is no conflicting repository in the directory, check the output of
git status. If it looks like the following, you are good to go to create a new repository as shown above:
$ git status
fatal: Not a git repository (or any of the parent directories): .git
Juan explains to Margaret how a nested repository is redundant and may cause confusion down the road. Margaret would like to remove the nested repository. How can Margaret undo her last
git initin the
Solution – USE WITH CAUTION!
Removing files from a git repository needs to be done with caution. To remove files from the working tree and not from your working directory, use
$ rm filename
The file being removed has to be in sync with the branch head with no updates. If there are updates, the file can be removed by force by using the
-foption. Similarly a directory can be removed from git using
rm -r dirnameor
rm -rf dirname.
Git keeps all of its files in the
.gitdirectory. To recover from this little mistake, Margaret Hamilton can just remove the
.gitfolder in the moons subdirectory by running the following command from inside the
$ rm -rf moons/.git
But be careful! Running this command in the wrong directory, will remove the entire Git history of a project you might want to keep. Therefore, always check your current directory using the command
git initinitializes a repository.
Git stores all of its repository data in the