How to increase the maximum number of open files on Fedora?

Question

I want to increase the maximum number of open files in Fedora 27, since the default settings are too low:

$ ulimit -Sn
1024
$ ulimit -Hn
4096

First, I ensure that the system-wide setting is high enough, by adding the following line to /etc/sysctl.conf:

fs.inotify.max_user_watches=524288
fs.file-max=100000

Then, I set the user-specific settings by adding the following lines to /etc/security/limits.conf (root must be added separately since the Wildcard matches all users except root):

*     soft  nofile 100000
*     hard  nofile 100000
root  soft  nofile 100000
root  hard  nofile 100000

To ensure that the above settings are actually loaded, I have added the following line to /etc/pam.d/login:

session required pam_limits.so

After rebooting my computer and logging in, I still get the same results for ulimit -Sn and ulimit -Hn. Only the system-wide setting have been set:

$ cat /proc/sys/fs/file-max
100000

I'm a bit at a loss as to what to do... Anybody have any ideas how I might diagnose/solve this?

Answer 1

The problem here is that the GUI (and gnome-terminal) are started by systemd --user, which does not read from /etc/security/limits.conf. Instead, you should edit /etc/systemd/user.conf and /etc/systemd/system.conf for the soft and hard limits, respectively, by appending e.g.

DefaultLimitNOFILE=100000

This same question has come up a few times on the StackExchange network; see e.g. this question for further discussion.

There are also bug reports for the issue, both for Ubuntu and Fedora.

Answer 2

Also, check your ~/.bashrc file for ulimit usage.

In my Fedora 38 I found that in my ~/.bashrc there where line

limit -n 4096

so updating it resolved the issue.