[patch] add pwait utility

[Eugene Grosbein]

On Fri, Nov 06, 2009 at 11:24:46PM +0100, Jilles Tjoelker wrote:

> 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

I've always missed such command exactly for later case :-)
Vote for it.

Eugene Grosbein