Ignoring Things

Last updated on 2024-03-12 | Edit this page

Overview

Questions

  • How can I tell Git to ignore files I don’t want to track?

Objectives

  • Configure Git to ignore specific files.
  • Explain why ignoring files can be useful.

What if we have files that we do not want Git to track for us, like backup files created by our editor or intermediate files created during data analysis? Let’s create a few dummy files:

BASH 

mkdir results
touch a.dat b.dat c.dat results/a.out results/b.out

and see what Git says:

BASH 

git status

OUTPUT 

On branch main
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	a.dat
	b.dat
	c.dat
	results/

nothing added to commit but untracked files present (use "git add" to track)

Putting these files under version control would be a waste of disk space. What’s worse, having them all listed could distract us from changes that actually matter, so let’s tell Git to ignore them.

We do this by creating a file in the root directory of our project called .gitignore:

BASH 

nano .gitignore
cat .gitignore

OUTPUT 

*.dat
results/

These patterns tell Git to ignore any file whose name ends in .dat and everything in the results directory. (If any of these files were already being tracked, Git would continue to track them.)

Once we have created this file, the output of git status is much cleaner:

BASH 

git status

OUTPUT 

On branch main
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	.gitignore

nothing added to commit but untracked files present (use "git add" to track)

The only thing Git notices now is the newly-created .gitignore file. You might think we wouldn’t want to track it, but everyone we’re sharing our repository with will probably want to ignore the same things that we’re ignoring. Let’s add and commit .gitignore:

BASH 

git add .gitignore
git commit -m "Ignore data files and the results folder."
git status

OUTPUT 

On branch main
nothing to commit, working directory clean

As a bonus, using .gitignore helps us avoid accidentally adding files to the repository that we don’t want to track:

BASH 

git add a.dat

OUTPUT 

The following paths are ignored by one of your .gitignore files:
a.dat
Use -f if you really want to add them.

If we really want to override our ignore settings, we can use git add -f to force Git to add something. For example, git add -f a.dat. We can also always see the status of ignored files if we want:

BASH 

git status --ignored

OUTPUT 

On branch main
Ignored files:
 (use "git add -f <file>..." to include in what will be committed)

        a.dat
        b.dat
        c.dat
        results/

nothing to commit, working directory clean

Ignoring Nested Files

Given a directory structure that looks like:

BASH 

results/data
results/plots

How would you ignore only results/plots and not results/data?

If you only want to ignore the contents of results/plots, you can change your .gitignore to ignore only the /plots/ subfolder by adding the following line to your .gitignore:

OUTPUT 

results/plots/

This line will ensure only the contents of results/plots is ignored, and not the contents of results/data.

As with most programming issues, there are a few alternative ways that one may ensure this ignore rule is followed. The “Ignoring Nested Files: Variation” exercise has a slightly different directory structure that presents an alternative solution. Further, the discussion page has more detail on ignore rules.

Including Specific Files

How would you ignore all .dat files in your root directory except for final.dat? Hint: Find out what ! (the exclamation point operator) does

You would add the following two lines to your .gitignore:

BASH 

*.dat           # ignore all data files
!final.dat      # except final.data

The exclamation point operator will include a previously excluded entry.

Note also that because you’ve previously committed .dat files in this lesson they will not be ignored with this new rule. Only future additions of .dat files added to the root directory will be ignored.

Ignoring Nested Files: Variation

Given a directory structure that looks similar to the earlier Nested Files exercise, but with a slightly different directory structure:

BASH 

results/data
results/images
results/plots
results/analysis

How would you ignore all of the contents in the results folder, but not results/data?

Hint: think a bit about how you created an exception with the ! operator before.

If you want to ignore the contents of results/ but not those of results/data/, you can change your .gitignore to ignore the contents of results folder, but create an exception for the contents of the results/data subfolder. Your .gitignore would look like this:

OUTPUT 

results/*               # ignore everything in results folder
!results/data/          # do not ignore results/data/ contents

Mac OS users and.DS_Store

When you do git status, Mac users may see a .DS_Store file showing as untracked. This a file that Mac OS creates in each directory.

To avoid committing this to your GitHub repository online you can add a line with .DS_Store to your .gitignore file.

Ignoring all data Files in a Directory

Assuming you have an empty .gitignore file, and given a directory structure that looks like:

BASH 

results/data/position/gps/a.dat
results/data/position/gps/b.dat
results/data/position/gps/c.dat
results/data/position/gps/info.txt
results/plots

What’s the shortest .gitignore rule you could write to ignore all .dat files in result/data/position/gps? Do not ignore the info.txt.

Appending results/data/position/gps/*.dat will match every file in results/data/position/gps that ends with .dat. The file results/data/position/gps/info.txt will not be ignored.

Ignoring all data Files in the repository

Let us assume you have many .dat files in different subdirectories of your repository. For example, you might have:

BASH 

results/a.dat
data/experiment_1/b.dat
data/experiment_2/c.dat
data/experiment_2/variation_1/d.dat

How do you ignore all the .dat files, without explicitly listing the names of the corresponding folders?

In the .gitignore file, write:

OUTPUT 

**/*.dat

This will ignore all the .dat files, regardless of their position in the directory tree. You can still include some specific exception with the exclamation point operator.

The Order of Rules

Given a .gitignore file with the following contents:

BASH 

*.dat
!*.dat

What will be the result?

The ! modifier will negate an entry from a previously defined ignore pattern. Because the !*.dat entry negates all of the previous .dat files in the .gitignore, none of them will be ignored, and all .dat files will be tracked.

Log Files

You wrote a script that creates many intermediate log-files of the form log_01, log_02, log_03, etc. You want to keep them but you do not want to track them through git.

  1. Write one .gitignore entry that excludes files of the form log_01, log_02, etc.
  2. Test your “ignore pattern” by creating some dummy files of the form log_01, etc.
  3. You find that the file log_01 is very important after all, add it to the tracked files without changing the .gitignore again.
  4. Discuss with your neighbor what other types of files could reside in your directory that you do not want to track and thus would exclude via .gitignore.
  1. append either log_* or log* as a new entry in your .gitignore
  2. track log_01 usinggit add -f log_01

Key Points

  • The .gitignore file tells Git what files to ignore.