The Git Index.Lock File

In this article, we will discuss the git index.lock file and its usage. Git has a powerful API and is the go-to source control.

If you are a regular user, you might have received the error message below.

fatal: Unable to create '.git/index.lock': File exists.

The message above calls to attention the creation of an index.lock file in our hidden .git directory. Let’s examine the index.lock file, the purpose it serves, and how we can deal with the error.

the index.lock File in Git

In our local machine, the .git directory is responsible for harboring the console’s working internals. Everything from branches, sub-modules, and commits live inside this directory.

Below is an example of our .git directory.

Git creates an index.lock in the .git file directory every time we run a command. If we were to run the git add . command to stage our local changes, Git would create an index.lock file while our command runs.

Git will then delete the file when the command is done executing. Git creates the index.lock file every time a command runs to prevent simultaneous changes to our repository.

It ensures that multiple processes are not happening simultaneously, which could leave our repo in an intermediate state.

fatal: Unable to create '.git/index.lock': File exists.

The error message above tells us that there is a process running, and we will have to wait to run another command.

As much as this is helpful, it is sometimes not entirely true. Sometimes you may get the error, and no command is underway.

There are several reasons this may happen. A good example is when a previous command did not end properly.

We have to manually remove the file by running the command below to remedy this.

rm .git/index.lock
#or
rm -f ./.git/index.lock

In a nutshell, the Git index.lock file is responsible for keeping transactional transparency in our local repository to ensure safety while working.

We resolve this error by letting the command complete or manually removing the file, as discussed above.