How to use git diff: commits, branches, files and side by side

`git diff` with no arguments shows changes you have not staged. `git diff --staged` shows what the next commit will contain, and `git diff main feature` compares two branches. Add -- path/to/file to any form to limit it to one file. Git itself has no side-by-side view in the terminal. For that you need git difftool or a Git GUI.

Which git diff command do I need?

How do I read git diff output?

diff --git a/src/search.ts b/src/search.ts
index 4e1f2a0..9b3c7d1 100644
--- a/src/search.ts
+++ b/src/search.ts
@@ -12,7 +12,7 @@ export function search(query: string) {
   const terms = tokenize(query);
-  return index.find(terms, { limit: 20 });
+  return index.find(terms, { limit: 50 });
 }

• --- and +++ name the old and new versions of the file.
• @@ -12,7 +12,7 @@ is a hunk header: 7 lines from line 12 in each version.
• Lines starting with - were removed, lines with + were added, the rest is context.

The reading diffs lesson practises this step by step.

How do I diff two commits?

# any two commits, older first
git diff 3e52f10 7c1d9ab

# the last commit against the one before it
git diff HEAD~1 HEAD

# one commit against its parent, with the message
git show 7c1d9ab

How do I diff two branches?

# the tips of both branches
git diff main feature

# only what feature added since it left main
git diff main...feature

# a remote branch
git fetch origin
git diff main origin/main

How do I diff one file?

# working copy against the last commit
git diff HEAD -- src/search.ts

# the same file on two branches
git diff main feature -- src/search.ts

# a file at two commits
git diff HEAD~3 HEAD -- src/search.ts

# two files outside any repository
git diff --no-index old.txt new.txt

How do I make git diff ignore whitespace?

These affect only what the diff shows. They do not change what gets staged or committed. -w is the one to reach for when a re-indent makes a whole file look changed.

How do I list only the changed files?

# names only
git diff --name-only main...feature

# names with A, M, D or R
git diff --name-status main...feature

# lines added and removed per file
git diff --stat main...feature

How do I see which words changed?

git diff --word-diff
git diff --color-words

Word diffs help with long lines, such as Markdown paragraphs, where one changed word marks the whole line as changed.

How do I get a side-by-side diff?

Plain git diff prints a single column and has no side-by-side option. You have three ways to get two columns: point git difftool at a diff program, install a terminal pager such as delta, or use a Git GUI.

# pick a tool once
git config --global diff.tool vimdiff

# open each changed file in it
git difftool main...feature

# skip the prompt for each file
git difftool -y

See choose and use a diff view and compare references for every option.