LinuxQuestions.org
Page 2 of 2 1 2
Show 50 post(s) from this thread on one page

LinuxQuestions.org (/questions/)
-   Slackware (https://www.linuxquestions.org/questions/slackware-14/)
-   -   How do I limit the amount of processes a user can run? (https://www.linuxquestions.org/questions/slackware-14/how-do-i-limit-the-amount-of-processes-a-user-can-run-309089/)

macemoneta 04-03-2005 09:57 AM
Quote:
Originally posted by chbin
since were on the topic of ulimits, is there a way to limit the cpu time of a particular process or particular user? I'm assuming there has to be, never tried it though.
Setting a CPU limit is tricky. The problem is that CPU time is cumulative. That is, the number of processes goes up and down, as does memory usage, but CPU only goes up.

It can be set (in seconds of CPU time) with:

ulimit -t 123

However, this is more useful when added as a "watchdog" to a process that shouldn't take more than a certain amount of time. For example:

Code:
# This should only run for 2 or three seconds
ulimit -S -t 10
While true
do
  if [ "$condition" == "done" ]
  then
    ulimit -S -t unlimited
    exit
  fi
...
done

houler 04-03-2005 04:08 PM
Quote:
Originally posted by SiegeX

Code:
if [[ "$USER" == "root" ]]; then
  ulimit -u 512
else
  ulimit -u 256
fi
Thanks for the script!

Code:
if[[ "$USER" == "houler" ]]; then
  ulimit -u 2
fi
How would one use a the "Hard" limit on that script (which I added in /etc/profile)? I know it's a -H, but I checked the bash man pages and I'm not really sure how it's used, here:

ulimit -H hard -u 256, says something about and invalid argument, and it sets the user processing limit back to 1000+

when I leave it to 'ulimit -u 2', it works fine.

SiegeX 04-03-2005 04:11 PM
Quote:
Originally posted by houler
How would one use a the "Hard" limit on that script (which I added in /etc/profile)? I know it's a -H, but I checked the bash man pages and I'm not really sure how it's used, here:

ulimit -H hard -u 256, says something about and invalid argument, and it sets the user processing limit back to 1000+

when I leave it to 'ulimit -u 2', it works fine.

Quoteth the bash man page
Quote:
If neither -H nor -S is specified, both the soft and hard limits are set
So no need to use -H

houler 04-03-2005 04:11 PM
Quote:
Originally posted by macemoneta
To limit execution of a large app in a loop, you can use memory limits as well:

# No core files by default
ulimit -c 0 > /dev/null 2>&1
# 768MB virtual memory limit
ulimit -v 786432 > /dev/null 2>&1
# 384MB resident memory limit
ulimit -m 393216 > /dev/null 2>&1
# 256 max processes per user
ulimit -u 256 >/dev/null 2>&1

Killing the loops isn't a problem. Many will fail on their own once they hit the resource limit. Those that don't can be killed from another login session (the limits are per session). System performance won't be an issue, unless you've set the limit too high. If neither -H nor -S is specified, both the soft and hard limits are set. The documentation for ulimit is in the bash man page (man bash).
Could I just plug that in /etc/profile?

keefaz 04-03-2005 04:40 PM
Better is to do it in slackware style, put those lines in a file like
/etc/profile.d/ulimit.sh

chmod +x it

houler 04-03-2005 05:22 PM
Ok I did it, thanks.

houler 04-04-2005 02:27 PM
A new problem arises with setting the ulimit after I make a chrooted ssh session:

Here's the story:


Basically, the shell is a"chroot-shell" script, Here is the script:

Code:
#!/bin/bash
if [ "$1" = "-c" ]; then
        i=0;
        PARAMS="";
        for param in $*; do
                if [ $i -gt 0 ]; then
                        PARAMS="$PARAMS $param";
                fi
                let i++;
        done;
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER -c "$PARAMS"
else
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER
fi;
When the user logs on, he's brought to this script first. The script logs in through "sudo" making the "ulimit" to like 512, after the user logs in, He's allowed to have 512 processes running and not the 256 I specified in /etc/profile:


Code:
if [[ "$USER" == "root" ]]; then
 ulimit -u 512
 else
 ulimit -u 256
fi

Any suggestion on how to circumvent this problem?

macemoneta 04-04-2005 03:43 PM
Quote:
Any suggestion on how to circumvent this problem?
Have sudo execute a script, passing it the parameters. In the script, set the ulimits you want, then execute the appropriate program based on the passed parameters.

houler 04-04-2005 04:11 PM
Quote:
Originally posted by macemoneta
Have sudo execute a script, passing it the parameters. In the script, set the ulimits you want, then execute the appropriate program based on the passed parameters.
How do i do that exactly?

Do you mean edit the script above, and somewhere along that script put down "sudo /bin/ulimits" where the 'ulimits' script will run

Code:
if [[ "$USER" == "root" ]]; then
ulimit -u 256
fi

Code:
#!/bin/bash
if [ "$1" = "-c" ]; then
        i=0;
        PARAMS="";
        for param in $*; do
                if [ $i -gt 0 ]; then
                        PARAMS="$PARAMS $param";
                fi
                let i++;
        done;
        sudo /bin/ulimits  <----------------HERE?
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER -c "$PARAMS"
else
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER
fi;
?

Sorry just a bit baffled because of the amount of "gaps" in the knowledge I know about scripts

macemoneta 04-04-2005 06:58 PM
More along the lines of:

Code:
...
done;
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER -c runUser "$PARAMS"
else
        sudo /usr/sbin/chroot /home/$USER /bin/su - $USER runUser bash
fi;
Where runUser is something along the lines of:

Code:
#!/bin/bash
# Set limits and execute
ulimit -u 256
$*

SiegeX 04-04-2005 07:49 PM
Actually I just realized that setting ulimit's for root is pointless because root can exceed even hard limits.

houler 04-04-2005 08:02 PM
Quote:
Originally posted by SiegeX
Actually I just realized that setting ulimit's for root is pointless because root can exceed even hard limits.
It's funny cuz I just realized that too not too long ago.

A way around it that I just figured out:

create a 'profile' file (or cp /etc/profile) and put it in /chroot-dir/etc/ and edit it

and add



Code:
# Ulimit settings for root
if [[ "$USER" == "root" ]]; then
 ulimit -u 512
 else
 ulimit -u 256
fi
It's working for now...


All times are GMT -5. The time now is 12:10 PM.
Page 2 of 2 1 2
Show 50 post(s) from this thread on one page