Ignoring Things

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.

RStudio creates a number of files that it uses to keep track of a project.

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.

In our files list notice that we have a .gitignore file.

This was automatically created when we setup specified that we wanted to create a project with a Git repository.

Let’s take a look at the file:

These patterns tell Git to ignore some specific files and any file whose name ends in .Rproj. (If any of these files were already being tracked, Git would continue to track them.)

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:

Tip: versioning disposable output

Generally you do not want to version control disposable output (or read-only data). You should modify the .gitignore file to tell Git to ignore these files and directories.

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

It is likely that we will generate a range of plots during our analysis that we may not want to track. We can expand our .gitignore to ignore any .png files and commit our changes.

I have added a .png file to the amr-data-dictionary directory. Notice that it does not appear in our Git tab files list.

We can try to add the file via the Terminal, Git will let us know that we have chosen not to track the file:

BASH

git add phd101212s.png

OUTPUT

The following paths are ignored by one of your .gitignore files:
phd101212s.png
hint: Use -f if you really want to add them.
hint: Turn this message off by running
hint: "git config advice.addIgnoredFile false"

You will notice from the output that it is possible to bypass the .gitignore file but it is not generally recommended.

Challenge

1. Create a new directory within your project called graphs.
2. Modify the .gitignore so that the graphs directory is not version controlled.

Solution to Challenge

This can be done in Rstudio:

R

dir.create("./graphs")

Then open up the .gitignore file from the right-hand panel of Rstudio and add graphs/ to the list of files to ignore.

Ignoring Nested Files

Given a directory structure that looks like:

BASH

analysis/data
analysis/plots

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

Show me the solution

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

OUTPUT

analysis/plots/

This line will ensure only the contents of analysis/plots is ignored, and not the contents of analysis/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 .png files in your root directory except for final.png? Hint: Find out what ! (the exclamation point operator) does

Show me the solution

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

OUTPUT

*.png           # ignore all png files
!final.png      # except final.png

The exclamation point operator will include a previously excluded entry.

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

Ignoring all data Files in a Directory

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

BASH

receipts/data/market_position/gps/a.dat
receipts/data/market_position/gps/b.dat
receipts/data/market_position/gps/c.dat
receipts/data/market_position/gps/info.txt
receipts/plots

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

Show me the solution

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

Ignoring all data Files in the repository

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

BASH

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

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

Show me the solution

In the .gitignore file, write:

OUTPUT

**/*.csv

This will ignore all the .csv 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

*.csv
!*.csv

What will be the result?

Show me the solution

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

Show me the solution

1. append either log_* or log* as a new entry in your .gitignore
2. track log_01 using git add -f log_01

Key Points

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