How to use git diff while excluding files

Understanding git diff

git diff is used to show the differences between two objects in a Git repository. These objects can be commits, branches, the working directory, and the staging area (index). By default, git diff will show you differences that are not yet staged.

Why exclude files or directories?

• Focus: Focus on significant changes by excluding files or directories that don't require review (like configuration files, logs, or dependencies).
• Noise reduction: Reduce clutter in diff outputs, making it easier to spot important changes.

How to exclude files and directories in git diff

Git does not include a built-in parameter specifically for excluding files directly in the git diff command, but you can achieve this by combining Git attributes or using pathspec filtering.

Method 1: Using .gitattributes to ignore files

A .gitattributes file is a configuration file used by Git to define attributes and settings for files in a repository. It allows users to specify custom behaviors such as text or binary handling, line ending normalization, and merge strategies for specific file types. This file is similar to the Git .config file, but specifically defines attributes and settings for files within a repository, while the git config generally deals with broader configuration settings for Git itself.

We can leverage a .gitattributes file to ignore files when executing the git diff command.

1. Create or modify a .gitattributes file in your repository root.

2. Add rules to ignore changes for specific files or directories. For example:

   Terminal

   # Ignore changes in specific config files
   secret.config -diff
   
   # Ignore changes in a specific directory
   logs/ -diff
   
   

   In this file, -diff tells Git to treat changes in these files as if they are binary and without any diff to output.

3. Test your configuration:

   Terminal

   git diff
   
   

   After setting up the .gitattributes file, changes to the specified files or directories should no longer appear in the diff.

Method 2: Excluding files using pathspec

Git supports pathspec patterns in many commands to limit the scope of certain Git operations. To exclude certain files or directories from your git diff output, use the :(exclude) pathspec.

1. Basic usage:

   Terminal

   git diff -- . ':(exclude)path/to/exclude'
   
   

   This command shows changes for all files in the current directory, except those in path/to/exclude.

2. Exclude multiple paths:

   Terminal

   git diff -- . ':(exclude)path/to/exclude' ':(exclude)another/path/to/exclude'
   
   

   Use multiple :(exclude) patterns to exclude many files or directories.

For further reading, see the official Git documentation.