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bantic
Asked: 2011-02-15 08:55:39 +0800 CST

open file descriptor limits.conf setting isn't read by ulimit even when pam_limits.so is required

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I am trying to raise the open file descriptor maximum for all users on an ubuntu machine.

I've added the following lines to /etc/security/limits.conf:

*               soft    nofile           100000
*               hard    nofile           100000

And, based on this question I've checked the /etc/pam.conf settings for pam_limits:

$ grep "pam_limits" /etc/pam.d/*
/etc/pam.d/atd:session    required   pam_limits.so
/etc/pam.d/common-session:session required pam_limits.so
/etc/pam.d/cron:session    required   pam_limits.so
/etc/pam.d/login:session    required   pam_limits.so
/etc/pam.d/sshd:session    required     pam_limits.so
/etc/pam.d/su:session    required   pam_limits.so
/etc/pam.d/sudo:session required pam_limits.so

And my file-max seems to be fine:

$ cat /proc/sys/fs/file-max 
762659

Yet I still have the default 1024 when I check ulimit -a:

$ ulimit -a | grep files
open files                      (-n) 1024

What else can I check?

linux ubuntu ulimit pam

2 Answers

  1. Best Answer

    I figured out that the system doesn't seem to like the wildcard for the user in limits.conf. Changing that to: root soft nofile 100000 and root hard nofile 100000 worked fine.

    • 15

  2. Adding another answer as, although bantic solved his problem, we had exactly same setup and symptoms. Ulimit soft and hard for nofile set to 100000 in limits.conf. No over-rides or other ulimit settings for users under /etc or in user's home and yet ulimit was low. Hard ulimit was 4096, soft ulimit was 1024.

    Centos 7.

    Actually adding an /etc/security/limits.d/20-nofile.conf with soft nofile 100000 and hard nofile 100000 seemed to solve it if you su as the user but not if you ssh in as the user.

    Eventually we found UsePAM: no in /etc/ssh/sshd_config Changing to UsePAM: yes and restarting sshd service solved it for us.

    • 0