Introduction

Sometimes git diff is technically correct but practically noisy. Lockfiles, generated assets, and machine-updated metadata can drown out the changes you actually want to review, so it helps to know the difference between excluding a file from one diff command and changing how Git displays diffs for that path in general.

Exclude a File for One Diff Command

If you want to hide a file from a single git diff invocation, use a pathspec exclusion. This is the cleanest option when you only want a temporary filter.

git diff -- . ':(exclude)package-lock.json'
git diff HEAD~1 HEAD -- . ':(exclude)dist/app.min.js'
git diff main...feature-branch -- . ':(exclude)docs/generated/api.md'

The -- . part tells Git to consider the current tree, and the :(exclude) pathspec removes matching paths from the result. This works well in ad hoc review commands, shell aliases, and pull-request preparation.

If you regularly exclude the same file, create an alias:

git config alias.review "diff -- . ':(exclude)package-lock.json'"
git review

That keeps the behavior local to your machine and avoids changing repository-wide settings.

Change Diff Behavior for Specific Files

If the goal is not "hide it this time" but "do not show a normal textual diff for this file type," use .gitattributes. This is appropriate for generated files, minified assets, or binary-like artifacts that should stay tracked but are not useful in patch form.

package-lock.json -diff
dist/*.min.js -diff
public/assets/* -diff

With -diff, Git stops producing a normal line-by-line patch for those paths. In many cases it will show them as binary changes or suppress the noisy textual output. This is a repository setting, so teammates get the same behavior after pulling the file.

That makes .gitattributes the right choice when the rule belongs to the project, not just to one developer.

Know What .gitignore Does Not Do

A common mistake is trying to solve this with .gitignore. That file only affects whether untracked files are considered for staging. It does not remove tracked files from git diff.

dist/
package-lock.json

The patterns above stop new untracked files from being suggested, but once a file is already tracked, Git will still diff it unless you use command filtering or attributes.

When to Use assume-unchanged or skip-worktree

You may see advice to use index flags such as assume-unchanged or skip-worktree. Those flags change how Git treats your working tree, but they are usually the wrong answer for review-oriented diff filtering.

git update-index --assume-unchanged path/to/file
git update-index --no-assume-unchanged path/to/file

These flags are local, easy to forget, and can create confusion when a file really does change. They are better viewed as niche performance or workflow tools, not as a general way to clean up diffs.

If the requirement is "exclude this from the diff I am looking at right now," prefer pathspec exclusion. If the requirement is "this file should not produce useful patch output for anyone," prefer .gitattributes.

A Practical Workflow

A good pattern for teams is:

1. Use git diff -- . ':(exclude)...' during local review when you want temporary focus.
2. Use .gitattributes when a file is consistently noisy for the whole repository.
3. Leave .gitignore for untracked-file control, not diff control.

That separation keeps your repository behavior predictable and your local review workflow flexible.

Common Pitfalls

• Using .gitignore to hide tracked files from diffs. It does not work for that purpose.
• Assuming .gitattributes completely removes the file from all comparisons. It changes diff behavior, but the file is still tracked.
• Reaching for assume-unchanged to solve a review problem. That can hide real edits and confuse later work.
• Forgetting that pathspec exclusions are command-specific. They do not persist unless you wrap them in an alias or script.
• Excluding too aggressively. If a generated file is a release artifact that must be reviewed, suppressing its diff may hide an important problem.

Summary

• Use :(exclude) pathspecs to omit files from a single git diff command.
• Use .gitattributes with -diff when a tracked file should not produce normal textual diffs.
• Do not rely on .gitignore for tracked-file diff filtering.
• Avoid assume-unchanged for normal review workflows unless you fully understand the tradeoffs.
• Pick the mechanism that matches the scope of the problem: one command, one developer, or the whole repository.