Setting system-wide ulimits (esp. # of open files)

[holger.rauch@arcor.de (Holger Rauch)]

Hi!

I'm running Debian testing in conjunction with kernel 2.6.0. I've got an
application demanding up to 32000 sockets in certain circumstances. So, I
wanted to set the # of open file descriptors on a system-wide basis. I'm
using bash as the shell for all my user accounts.

Here's what I tried:

1. Look up the value of /proc/sys/fs/file-max just to be sure => yields
   104849. So, that should be large enough.

2. Tried to modify the value for "ulimit -n" from the shell prompt as a
   regular user => got "Operation not permitted"

3. a) Modified /etc/security/limits.conf so that it now contains the
      following line:

	*               soft    nofile          32000

   b) Modified certain PAM-related files below /etc/pam.d so that they now
      contain the line (the modification consisted of uncommenting the
      according line)

	session    required   pam_limits.so

     I changed the following files:

	/etc/pam.d/login
	/etc/pam.d/su

   c) However, after logging in from a different console, the command
      "ulimit -a" still outputs:

	open files                    (-n) 1024

4. Googling for "debian increasing ulimits" (and similar things) only
   revealed that it's possible to *lower* a certain ulimit value as a
   regular user (however, that's not what I want; I want to *increase* a
   certain ulimit value, most notably the # of open file descriptors).

Any other ideas on what else I could try in order to increase the #
of open file descriptors to 32000 for all users and why the approach with
editing /etc/security/limits.conf didn't work (and what I could do to
get it to do what I want :-) )?

Thanks in advance for any hints/pointers!

Kind regards,

	Holger