[patch] add pwait utility

[Jilles Tjoelker]

I propose adding a small new utility to /usr/bin: pwait. Similar to the
Solaris utility of the same name, it waits for any process to terminate.
Some use cases I have in mind:

* rc.subr's wait_for_pids. This is a cleaner and more efficient fix for
  PR conf/132766. In the rare case that /usr is not available, the old
  sleep(1) method can be used.
* interactive use, e.g. to shut down the computer when some task is done
  even if the task is already running

-- 
Jilles Tjoelker
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pwait.patch
Type: text/x-diff
Size: 7561 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-hackers/attachments/20091106/75d12b9b/pwait.bin