patch
patch -pnum < patchfile
patch takes a patch file patchfile containing a difference listing produced by the diff program and applies those differences to one or more original files, producing patched versions.
Commonly used by version control systems. Provides a mechanism for applying a list of differences to one file to create another.
Examples
Create a file containing the differences between two file versions.
diff -u dictionary.xml dictionary.xml.new > dictionary.xml.patch
Apply the patch created above
patch < dictionary.xml.patch
