diff

Additional Notes

diff is a text-processing command used to compare files line by line. It produces output showing line-level changes between files, and supports several output formats including normal, unified (-u), and context (-c). Unified diffs can be applied later with patch.

Syntax

diff [options] [file...]

Parameters

• options: Flags that change how diff behaves.
• file: Text file to read or process.

Common Options

• -u: Show unified diff output.
• -r: Compare directories recursively.
• -q: Report only whether files differ.
• --color: Colorize output when supported.

Examples

diff old.txt new.txt
diff -u old.txt new.txt
diff -qr dir-a dir-b

Practical Notes

Unified diffs from diff -u are readable and can often be applied with patch.