Add pwait utility, which waits for any process to terminate.

This is similar to the Solaris utility of the same name.

Some use cases:
* rc.subr's wait_for_pids
* interactive use, e.g. to shut down the computer when some task is done
  even if the task is already running

Discussed on:	hackers@

1 files changed, 78 insertions, 0 deletions

diff --git a/bin/pwait/pwait.1 b/bin/pwait/pwait.1
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+.\"
+.\" Copyright (c) 2004-2009, Jilles Tjoelker
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with
+.\" or without modification, are permitted provided that the
+.\" following conditions are met:
+.\"
+.\" 1. Redistributions of source code must retain the above
+.\"    copyright notice, this list of conditions and the
+.\"    following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the
+.\"    above copyright notice, this list of conditions and
+.\"    the following disclaimer in the documentation and/or
+.\"    other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+.\" CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
+.\" WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+.\" PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+.\" COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
+.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+.\" USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+.\" OF SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd November 1, 2009
+.Os
+.Dt PWAIT 1
+.Sh NAME
+.Nm pwait
+.Nd wait for processes to terminate
+.Sh SYNOPSIS
+.Nm
+.Op Fl v
+.Ar pid
+\&...
+.Sh DESCRIPTION
+The
+.Nm
+utility will wait until each of the given processes has terminated. 
+.Pp
+The following option is available:
+.Bl -tag -width indent
+.It Fl v
+Print the exit status when each process terminates.
+.El
+.Sh DIAGNOSTICS
+.Pp
+The
+.Nm
+utility returns 0 on success, and >0 if an error occurs.
+.Pp
+Invalid pids elicit a warning message but are otherwise ignored.
+.Sh SEE ALSO
+.Xr kill 1 ,
+.Xr pkill 1 ,
+.Xr ps 1 ,
+.Xr wait 1 ,
+.Xr kqueue 2
+.Sh NOTES
+.Nm
+is not a substitute for the
+.Xr wait 1
+builtin
+as it will not clean up any zombies or state in the parent process.
+.Sh HISTORY
+A
+.Nm
+command first appeared in SunOS 5.8.