How to Use a .gitignore File

When you make commits in a git repository, you choose which files to stage and commit by using git add FILENAME.You can also use git add . to stage all files in the current directory, and then git commit.

But what if there are some files that you never want to commit?

That’s where a .gitignore file comes in handy. It lets Git know that it should ignore certain files or folders and not track them.

Ignored files are tracked in a special file named .gitignore .

There is no explicit git ignore command: instead the .gitignore file must be edited and committed by hand when you have new files that you wish to ignore.

What is a .gitignore file?

A .gitignore file is a plain text file where each line contains a pattern for files/directories to ignore.

Generally, A .gitignore file is placed in the root folder of the repository. The patterns in the files are relative to the location of the .gitignore file.

For example. Here is the file tree of my git repository.

git repository
   - .DS_Store
   - data/
         - data1.txt
         - data2.txt
   - file1.py
   - file2.py
   - log1.log
   - log2.log
   - .git/
   - .gitignore

And here is the content of a .gitignore file.

.DS_Store
/Data/
*.log

Patterns of ignoring files/folders.

.gitignore files contain patterns that are matched against file names in your repository to determine whether or not they should be ignored.

1. Ignore a single file

The easiest pattern is a literal file name, for example:

.DS_Store

2. Ignore an entire directory

You can ignore entire directories, just by including their paths and putting a / on the end:

Data/

3. Ignore a file type

The * matches 0 or more characters (except the /). So, for example, *.log matches any file ending with the .log extension.

*.log

4. Add an exception

You can add an exception (using !) to the preceding rule to track a specific

 file !package.json

Ref:

.gitignore file — ignoring files in Git | Atlassian Git Tutorial
https://www.atlassian.com/git/tutorials/saving-changes/gitignore

Ignore files in your Git repo — Azure Repos | Microsoft Docs
https://docs.microsoft.com/en-us/azure/devops/repos/git/ignore-files?view=azure-devops&tabs=command-line

https://www.pluralsight.com/guides/how-to-use-gitignore-file