Introducing Version Control with Git

Renaming and removing files

So far we have only added and changed files in our version controlled working directory, and git was clever enough to work out what it needed to do. However, git does not know how to automatically work out when you have renamed or removed files.

Renaming files

To rename a file, you have to use git mv. We are going to rename the file something.md to background.md. To do this, type

git mv something.md background.md

If you now type ls you should see that something.md has been renamed (moved) to background.md.

Now, git status should show something like

On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
    renamed:    something.md -> background.md

To commit this change, use git commit -a as normal, remembering to add a suitable commit message, e.g.

Have renamed something.md to background.md to better reflect
the contents of the file

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch main
# Changes to be committed:
#       renamed:    something.md -> background.md
#

A quick check of git status should then show that your working directory is clean.

Removing files

To remove a file use git rm. To remove background.md we just need to type;

git rm background.md

If you now type ls you should see that background.md has been removed.

Now git status should show something like

On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
    deleted:    background.md

Note that this has removed the file from the working directory. The file will still exist in old versions stored in the repository. We can restore this file using;

git checkout main background.md

This is the real power of using version control. It is very difficult to actually lose files or accidentally delete data. As long as you have saved a snapshot version into the repository, then you will always be able to restore the data.

Indeed, git even tries to prevent you from losing data that is not saved to the repository. The command git rm FILE will only work if FILE is tracked by git and has no changes compared to the last version saved in the repository. To force removal of a file in this case, you need to use git rm -f FILE, where the flag -f means "force".

Git Cheat Sheet

We have two new commands, git mv for renaming (moving) files, and git rm for removing files.

Git Cheat Sheet

(1)  git init              : Tell git to start version controlling the files in a directory
                             (initialises git in a directory)
(2)  git status            : Tell git to print the status of the files in the version 
                             controlled directory.
(3)  git add               : Tell git to start monitoring (tracking) the versions of a new
                             file, e.g. `git add README.md` will tell git to track `README.md`   
(4)  git commit -a         : Tell git to save a new snapshot version of all of the tracked
                             files in the directory. The `-a` means "all files". You can
                             commit new versions of individual files if you want, but this
                             is not recommended.
(5)  git diff              : Tell git to show the differences between the files in the working
                             directory and the last saved version in the git repository. This will
                             show the differences for all tracked files. Use
                             `git diff FILENAME` to limit to only the file `FILENAME`
(6a) git checkout VERSION FILENAME  : Tell git to bring `VERSION` version of `FILENAME` into the 
                                      current working directory. If `VERSION` is `main` then 
                                      restore the last version of `FILENAME` that was saved
                                      to the repository.
(6b) git checkout VERSION  : Tell git to change the working directory back to a specific `VERSION`
                             number. If `VERSION` is `main`, then return the working directory to
                             the last saved version in the repository.
(7)  git log               : Print a log of the versions in the repository. Use `git log -n N`
                             to limit to the last `N` versions. You may need to use `q` to exit
                             from the text viewer if there are a lot of versions to print.
(8)  git mv OLD NEW        : Rename a file from name `OLD` to name `NEW`.
(9)  git rm FILENAME       : Remove the file `FILENAME` from the working directory (it still exists
                             in the repository). Will only work if the file is tracked by
                             git and doesn't have any changes. Use `-f` to force removal of files. 

Exercise

Create a new file called notes.md, fill it with some text, then add it and commit it to the repository.

Use git mv to rename notes.md to more_notes.md and commit this change to the repository.

Use git rm to remove more_notes.md and commit this change to the repository.

Use git checkout VERSION FILENAME to check out an old version of notes.md to the current working directory and then commit this change to the repository.

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