Recursive renice?

[Zev Thompson]

Hi all,

I'm curious whether there's an easy way to renice(8) a process and all 
of its children in one simple command. For example, I might start a 
recursive make, which spawns lots of processes, and want them all to 
change priority at once.

The command I want is this:

renice +10 -r process-ID

Except for the fact that -r is not a valid flag. The pstree utility, in 
the ports, seems like it might be a good start to hack this 
functionality in. I searched google for "recursive renice" and found 
someone had made a sed script, but it's for linux, where the pstree 
output is different. Here's some example pstree output:

  |             \-+- 14187 zevt gmake
  |               \-+- 14189 zevt gmake all-recursive
  |                 \-+- 14190 zevt /bin/sh -c set fnord ;
  |                   \-+- 14807 zevt /bin/sh -c set fnord ;
[etc.]

Google result that's relevant:
http://mail.gnu.org/archive/html/bug-coreutils/2003-10/msg00033.html

Any hints? Thanks in advance to any answers.

Zev