This is happening on Ubuntu Release 12.04 (precise) 64-bit Kernel Linux 3.2.0-25-virtual
I'm trying to increase the number of open files allowed for a user. This is for my eclipse java application 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 rebooted 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
But even I get eclipse to run as root, my application still crashes because of "Too Many Open File" exception!
So far, I haven't found any way to increase the open files limit for a non-root user.
How should I properly do this? I have looked at several other posts but no luck!
Best Answer
The
ulimit
command by default changes the HARD limits, which you (a user) can lower, but cannot raise.Use the -S option to change the SOFT limit, which can range from 0-{HARD}.
I have actually aliased
ulimit
toulimit -S
, so it defaults to the soft limits all the time.As for your issue, you're missing a column in your entries in
/etc/security/limits.conf
.There should be FOUR columns, but the first is missing in your example.
The first column describes WHO the limit is to apply for. '*' is a wildcard, meaning all users. To raise the limits for root, you have to explicitly enter 'root' instead of '*'.
You also need to edit
/etc/pam.d/common-session*
and add the following line to the end: