Git Diff

What is git diff?

git diff shows the exact lines that changed in your files.

Use it to check your work before you stage or commit it:

• git diff: changes you have not staged yet
• git diff --staged: changes that are staged and will go into the next commit
• git diff <commit> <commit>: changes between two commits
• git diff <branch>..<branch>: changes between two branches

See Unstaged Changes

Change a line in index.html, then run git diff:

git diff
diff --git a/index.html b/index.html
index 1be8d65..417ac8f 100644
--- a/index.html
+++ b/index.html
@@ -1,2 +1,2 @@
-Hello World
+Hello Git
 Welcome to Git

How to Read the Output

• --- a/index.html and +++ b/index.html: the old and the new version of the file
• @@ -1,2 +1,2 @@: where the change is. 2 lines starting at line 1 in the old version, 2 lines starting at line 1 in the new
• Lines starting with - were removed
• Lines starting with + were added
• Lines starting with a space did not change. They are shown for context

If the output is long, Git opens it in a pager. Use the arrow keys to scroll, and press q to quit.

See Staged Changes

After you stage a file with git add, plain git diff shows nothing for it. Use --staged (or its older name --cached) to see what will be committed:

git add index.html
git diff
git diff --staged
diff --git a/index.html b/index.html
index 1be8d65..417ac8f 100644
--- a/index.html
+++ b/index.html
@@ -1,2 +1,2 @@
-Hello World
+Hello Git
 Welcome to Git

Only File Names (--stat and --name-only)

Use --stat to see which files changed and how many lines, without the full diff:

git diff HEAD --stat
 index.html | 2 +-
 style.css  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

Comparing with HEAD (the last commit) shows both staged and unstaged changes. Use --name-only to list just the file names:

git diff HEAD --name-only
index.html
style.css

Compare Two Commits

Give git diff two commits to see what changed between them. HEAD~1 means "the commit before the last one":

git diff HEAD~1 HEAD
diff --git a/index.html b/index.html
index 1be8d65..9c9e0c6 100644
--- a/index.html
+++ b/index.html
@@ -1,2 +1,3 @@
 Hello World
 Welcome to Git
+Read the docs

Compare Two Branches

Use two dots between branch names to see how one branch differs from another:

git diff main..new-title --stat
 index.html | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Ignore Spaces

Use -w to ignore changes that only add or remove spaces. This is useful when someone has re-indented a file:

git diff -w