Dtyjlui

I'm trying to increase open file limit for root user as well as non-root user via /etc/security/limits.conf. But, cannot get past 999999, anything above this value reverts to default 1024 nor I can set it to unlimited

Here is my limits.conf

* hard nofile 999999

* hard nofile 999999

root hard nofile 999999

root soft nofile 999999

The above works fine and ulimit -n return 999999.

But, if I make the value one step higher or to unlimited or -1 or infinity it doesn't work. ulimit -n return 1024

I refered here: limits.conf - configuration file for the pam_limits module | Ubuntu Manpage

Thanks

I know it's 10 months late, but you've set the hard limit twice for all users. Change the second line to be a soft ulimit.

* hard nofile 999999

* soft nofile 999999

root hard nofile 999999

root soft nofile 999999

After doing this you should see:

$ ulimit -n

999999

$ 

Your file should have always worked for root as the limits were correctly defined.

Furthermore you can't use -1, infinity, unlimited or the like, you must use a literal value. The max supported value for this is defined in the kernel and is exposed in /proc/sys/fs/nr_open. In my centos 7 & debian strech environments I get the same value:

$ cat /proc/sys/fs/nr_open

1048576

$

You also have to start a new session for the limits to update.

There are three files to modify to get this to work:

• /etc/security/limits.conf


• /etc/pam.d/common-session


• /etc/pam.d/common-session-noninteractive

You have already added the required lines in the first file, then in the other two files this line is needed:

session required pam_limits.so

Please note:

The thing that most resources neglect to emphasize, is that your limits can really easily be modified by anything responsible for execution of your processes. If ulimit -n (run as the correct user) is giving you the number you just set, but cat /proc/{process_id}/limits is still printing the low number, you almost certainly have a process manager, an init script, or something similar messing your limits up. You also need to keep in mind that processes inherit the limits of the parent process.

Hence if such a process exists then you will have to modify the config file to get it to work.

Source:
https://underyx.me/2015/05/18/raising-the-maximum-number-of-file-descriptors