| of course, you can always do this:
| 
|    # cd /usr/src
|    # find . -name Makefile | xargs grep ^.PATH | grep cksum

You should never use xargs like that, because it might call
grep with only one argument in which case a filename would not be
printened. Instead, use

  find . -name Makefile | xargs grep ^.PATH /dev/null | grep cksum
                                            ^^^^^^^^^

--jhawk