patch
patch takes comparison output produced by diff and applies
the differences to a copy of the original file, producing a patched
version. With patch, you can distribute just the changes to a
set of files instead of distributing the entire file set; your
correspondents can apply patch to update their copy of the files
with your changes. patch automatically determines the diff
format, skips any leading or trailing headers, and uses the headers to
determine which file to patch. This lets your correspondents feed an
article or message containing a difference listing directly to
patch.
patch detects and warns about common problems like forward
patches. It saves the original version of the files it patches, and
saves any patches that it could not apply. It can also maintain a
patchlevel.h file to ensures that your correspondents apply
diffs in the proper order.
patch accepts a series of diffs in its standard input, usually
separated by headers that specify which file to patch. It applies
diff hunks (see section Hunks) one by one. If a hunk does not
exactly match the original file, patch uses heuristics to try to
patch the file as well as it can. If no approximate match can be found,
patch rejects the hunk and skips to the next hunk. patch
normally replaces each file f with its new version, saving the
original file in `f.orig', and putting reject hunks (if any)
into `f.rej'.
See section Invoking patch, for detailed information on the options to
patch. See section Backup File Names, for more information on how
patch names backup files. See section Reject File Names, for more information
on where patch puts reject hunks.
patch input.
patch can produce.