cdiff - context diff
cdiff [-cn] oldfile newfile
-c Provide n lines of context
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.
cmp(1), diff(1), patch(1).