> excuse me, i have not explained me clearly. i don't try to limit. In 
> fact it is limited by root but more try to configure pkgsrc/bmake/etc. 
> not to make too many fork, else i have the above message.
> i have a 'ulimit -u 50' made by root, and when i compile, bmake or bmake 
> readme (at pkgsrc root for example), i get "sh: fork failed - too many 
> processes"

The message means that you reached either your user limit
of number of your processes, or system limit. I guess that
user limit is more likely, since it's only 64 by default.

Before you run the bmake or configure, try running ulimit
in your shell, as you. If you run it as root, you'd only
change limits for the shell you run as root, it wouldn't
influence system limits.

Try
> ulimit -a

That should show you your current user limits.

Then try
> ulimit -n 512

that should bump number of files (nofiles(descripriptors)).

Jaromir
-- 
Jaromir Dolecek <jdolecek@NetBSD.org>            http://www.NetBSD.org/
-=- We should be mindful of the potential goal, but as the tantric    -=-
-=- Buddhist masters say, ``You may notice during meditation that you -=-
-=- sometimes levitate or glow.   Do not let this distract you.''     -=-