Command:   cdiff - context diff
Syntax:    cdiff [-cn] oldfile newfile
Flags:     -c  Provide n lines of context
Examples:  cdiff old new >f         # Write context diff on f
           cdiff -c1 old new >f     # Use only 1 line of context

     Cdiff produces a context diff by first running diff and then adding
context.  Some  update  programs,  like  patch, can use context diffs to
update files, even in the presence of other, independent changes.