/etc/security/limits.conf not applied

Question

I have /etc/security/limits.conf, that seems not been applied:

a soft nofile 1048576 # default: 1024 a hard nofile 2097152 a soft noproc 262144 # default 128039 a hard noproc 524288

Where a is my username, when I run ulimit -Hn and ulimit -Sn, it shows:

4096 1024

There's only one other file in the /etc/security/limits.d that the content is:

scylla - core unlimited scylla - memlock unlimited scylla - nofile 200000 scylla - as unlimited scylla - nproc 8096

I tried also append those values to /etc/security/limits.conf then restarting, and do this:

echo ' session required pam_limits.so ' | sudo tee -a /etc/pam.d/common-session

but it didn't work. My OS is Ubuntu 17.04.

Calum McConnell · Accepted Answer · 2024-10-20 13:30:23Z

There's a bug since Ubuntu 16 apparently.

Basically:

Edit /etc/systemd/user.conf for the limit on user services, and add DefaultLimitNOFILE=1048576.
Edit /etc/systemd/system.conf for the limit on system services and things they create, and add DefaultLimitNOFILE=2097152.

You need to edit both files.

To set a separate soft and hard limit, specify them like soft:hard, eg 4096:16384.

Credit goes to @mkasberg.

this works to set ulimit values, but one thing to notice: systemd has only "infinity" value to set ulimit to "unlimited", there is apparently no "unlimited" value in systemd 252 (252-18.el9) — xealits
– xealits, Commented Dec 6, 2023 at 16:52

Mateen Ulhaq · Accepted Answer · 2023-12-18 14:41:41Z

It is recommended to create /etc/systemd/*.d/ directories instead of editing /etc/systemd/system.conf and /etc/systemd/user.conf directly.

Create a new file /etc/systemd/system.conf.d/limits.conf with these contents:

[Manager] DefaultLimitNOFILE=1048576:2097152 DefaultLimitNPROC=262144:524288

Run systemctl daemon-reexec as root.
Logout and login again.
Check your new limits with either ulimit -a or ulimit -n and ulimit -u for max open files and max processes, respectively.

2 Answers 2