Editing Diff (section)

=== Extensions ===
There are some modifications and extensions to the diff formats that are used and understood by certain programs and in certain contexts. For example, some [[revision control]] systems—such as [[Subversion (software)|Subversion]]—specify a version number, "working copy", or any other comment instead of or in addition to a timestamp in the diff's header section.

Some tools allow diffs for several different files to be merged into one, using a header for each modified file that may look something like this:

 Index: path/to/file.cpp

The special case of files that do not end in a newline is not handled. Neither the unidiff utility nor the POSIX diff standard define a way to handle this type of files. (Indeed, such files are not "text" files by strict POSIX definitions.<ref>http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_403 {{Webarchive|url=https://web.archive.org/web/20130429195728/http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_403 |date=2013-04-29 }} Section 3.206</ref>) GNU diff and git produce "\ No newline at end of file" (or a translated version) as a diagnostic, but this behavior is not portable.<ref>{{cite web |title=Incomplete Lines (Comparing and Merging Files) |url=https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html |website=www.gnu.org}}</ref> GNU patch does not seem to handle this case, while git-apply does.<ref>{{cite web |title=git: apply.c |url=https://github.com/git/git/blob/69c786637d7a7fe3b2b8f7d989af095f5f49c3a8/apply.c#LL2901C35-L2901C39 |publisher=Git |date=8 May 2023}}</ref>

The [[Patch (Unix)|patch]] program does not necessarily recognize implementation-specific diff output. GNU patch is, however, known to recognize git patches and act a little differently.<ref>{{cite web |title=patch.c\src - patch.git - GNU patch |url=https://git.savannah.gnu.org/cgit/patch.git/tree/src/patch.c?id=c835ecc67b7e37c0d0b7dd7e032209fdaa285808#n1919 |website=git.savannah.gnu.org |quote=In git-style diffs, the "before" state of each patch refers to the initial state before modifying any files,..}}</ref>