This is happening on Ubuntu 9.10 server

I'm trying to increase the number of open files allowed for a user. This is for an nginx webserver where the current limit of 1024 is not enough.

According to the posts I've found so far, I should be able to put lines into /etc/security/limits.conf like this;


* soft nofile 4096
* hard nofile 4096


...to increase the number of open files allowed for all users.

But, that's not working for me, and I think the problem is not related to that file.

For all users, the default limit is 1024, regardless of what is in /etc/security/limits.conf (I have been rebooting after changing that file)


$ ulimit -n
1024


Now, despite the entries in /etc/security/limits.conf I can't increase that;


$ ulimit -n 2048
-bash: ulimit: open files: cannot modify limit: Operation not permitted


The weird part is that I can change the limit *downwards*, but can't change it upwards - even to go back to a number which is below the original limit;


$ ulimit -n 800
$ ulimit -n
800

$ ulimit -n 900
-bash: ulimit: open files: cannot modify limit: Operation not permitted


As root, I can change that limit to whatever I want, up or down. It doesn't even seem to care about the supposedly system-wide limit in /proc/sys/fs/file-max


# cat /proc/sys/fs/file-max
188897

# ulimit -n 188898
# ulimit -n
188898


So far, I haven't found any way to increase the open files limit for a non-root user, and I really don't want to be running my webserver as root.

Does anyone have any ideas?

David