Diff

Diff is a class of programming utilities that compares two or more files for changes or differences between them and frequently offer methods to merge one or more files together as well. This tool is both available as a separate utility but is frequently also embedded into IDEs and text editors.

File output

Edit script

can be generated by modern implementations with the -e option

Context format

introduced with 2.8 BSD (July 1981)

Unified format

introduced by unidiff (Aug 1990), GNU diff 1.15 (Jan 1991)

Although many newer diff tools have modified the output file format for more flexibility, the original diff output file format has become something of a standard since a number of utilities and systems can open up diff files for further processing or visualisation.

Diff tools

OS/2 diff tools

• Araxis PMDiff - last version 4.0c freeware
• GNU diffutils - Open source

Java diff tools

• Guiffy - Commercial

Text editors with diff file support

• Elvis - diff syntax support included by default
• FTE - Has support for syntax highlighting, code folding and syntax-aware autoindent.