[2] Wall's code remains the basis of "patch" programs provided in OpenBSD,[3] FreeBSD,[4] and schilytools.

[dubious – discuss] The GNU project/FSF maintains its patch, forked from the Larry Wall version.

Because of this property, context and unified diffs are the preferred form of patches for submission to many software projects.

Outsiders can download the latest publicly available source code, make modifications to it, and send them, in diff form, to the development team.

Patches to files in subdirectories require the additional -pnumber option, where number is 1 if the base directory of the source tree is included in the diff, and 0 otherwise.

Originally written for Unix and Unix-like systems, patch has also been ported to Windows and many other platforms.