topic Re: ulimit: open files: cannot modify limit: Operation not permitted in Operating System - Linux

ulimit: open files: cannot modify limit: Operation not permitted

Carme Torca — Fri, 06 Jun 2008 11:55:25 GMT

Hi,

I have one user USER1, and when I go into the system by ssh and do #ulimit -a (its has
open files (-n) 1024)
and if I do #ulimit -n 16384, its outs:

"ulimit: open files: cannot modify limit: Operation not permitted"

But if I enter by root and then su - USER1, its has (open files 16384, because I have one ulimit -n 16384 on the .bash_profile.

What is happenning?. How could I change this when I enter by ssh directly by the USER1??

Thanks a lot of,
Carmen.

Re: ulimit: open files: cannot modify limit: Operation not permitted

Steven E. Protter — Fri, 06 Jun 2008 12:19:36 GMT

Shalom,

You may have a kernel limit interfering with your ulimit command.

You could try unlimited instead of a number.

You may want to check maxupcr and other kernel parameters that control file open.

SEP

Re: ulimit: open files: cannot modify limit: Operation not permitted

Matti_Kurkela — Fri, 06 Jun 2008 12:27:47 GMT

For each ulimit variable, there are actually two limits: a soft limit and a hard limit.

A normal user can adjust the soft limit freely in the range of 0....
A normal user can adjust the hard limit too, but can only decrease it. You must be root to increase the hard limit from its default value.

To see the hard limit values, run "ulimit -H -a".

The limit values are inherited from the parent process to the child process: you could add the command to increase the hard limit to the sshd startup script, so that sshd and all sessions started through it will inherit the increased hard limit. After that, you should be able to increase the soft limit as a normal user.

Alternatively, some Linux distributions have PAM modules (pam_limit.so) that can adjust the limit values at login time, if configured to do so.

MK

Re: ulimit: open files: cannot modify limit: Operation not permitted

Jeeshan — Fri, 06 Jun 2008 16:25:25 GMT

Hi

Check the kernel parameter using command related to no. of open file max

#sysctl -a|grep fs.file-max

if the parameter is >= 16384 than you can set like this other wise you need to change the kernel parameter.