Master Git Diff With These Not-So-Known Commands

Spot errors before pushing to save time while reviewing your own pull requests

THE PROBLEM

You spend a lot of time reviewing your own pull request on Github before asking for a review and you always find stuff that needs to be changed. So you need to add/edit commits, losing lots of time.

A SOLUTION

Before committing, make good use of git diff, so you avoid having to change code later.

Here are some not-so-known git tips, sorted from more common to more uncommon:

Changes on staged or unstaged files

1. Show all unstaged changes since the last commit:

git diff

2. Show all staged changes since the last commit:

git diff --cached

3. Show all staged and unstaged changes since the last commit:

git diff HEAD

Revision targeting

1. Show changes since a specific commit:

git log --oneline
# 4833545 cleanup
# c3a1ee6 add navbar
# ca2f968 initial commit

git diff ca2f968

2. Show changes since the last n commits, e.g. 2:

git diff HEAD~2

Single file

1. Show changes on a single file since the last commit:

git diff script.js

2. Show changes on a single file since a specific commit:

git log --oneline
# 4833545 cleanup
# c3a1ee6 add navbar
# ca2f968 initial commit

git diff ca2f968 script.js

Summary of changes

To be run from your feature branch.

1. Show all changes over a specific branch (GitHub PR diff):

git diff master

2. Show changed files with a number of changed lines over a specific branch:

git diff master --stat

3. Show a **one-line summary of the changes **over a specific branch:

git diff master --shortstat

BONUS

Finally, here’s a neat trick by Shime.sh, to make your diffs more readable by removing the + and - symbols, since they are colored anyway!

git config --global pager.diff 'sed "s/^\([^-+ ]*\)[-+ ]/\\1/"'

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