diff Cheatsheet
Basic Usage
Compare files and save output.
| Command | Description |
|---|---|
diff file1 file2
|
Compare two files (normal format) |
diff -u file1 file2 |
Unified format (most common) |
diff -c file1 file2 |
Context format |
diff -y file1 file2 |
Side-by-side format |
diff file1 file2 > file.patch |
Save diff to a patch file |
Output Symbols
What each symbol means in the diff output.
| Symbol | Format | Meaning |
|---|---|---|
< |
normal | Line from file1 (removed) |
> |
normal | Line from file2 (added) |
- |
unified/context | Line removed |
+ |
unified/context | Line added |
! |
context | Line changed |
@@ |
unified | Hunk header with line numbers |
Directory Comparison
Compare entire directory trees.
| Command | Description |
|---|---|
diff -r dir1 dir2 |
Compare directories recursively |
diff -rq dir1 dir2 |
Only report which files differ |
diff -rN dir1 dir2 |
Treat absent files as empty |
diff -rNu dir1 dir2 |
Unified recursive diff (for patches) |
Filtering
Ignore specific types of differences.
| Option | Description |
|---|---|
-i |
Ignore case differences |
-w |
Ignore all whitespace |
-b |
Ignore changes in whitespace amount |
-B |
Ignore blank lines |
--strip-trailing-cr |
Ignore Windows carriage returns |
Common Options
| Option | Description |
|---|---|
-u |
Unified format |
-c |
Context format |
-y |
Side-by-side format |
-U n |
Show n lines of context (default: 3) |
-C n |
Show n lines of context (context format) |
-W n |
Set column width for side-by-side |
-s |
Report when files are identical |
--color |
Colorize output |
-q |
Brief output (only whether files differ) |
Patch Workflow
Create and apply patches with diff and patch.
| Command | Description |
|---|---|
diff -u file1 file2 > file.patch |
Create a patch for a single file |
diff -rNu dir1 dir2 > dir.patch |
Create a patch for a directory |
patch file1 < file.patch |
Apply patch to file1 |
patch -p1 < dir.patch |
Apply directory patch |
patch -R file1 < file.patch |
Reverse (undo) a patch |
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