How to set ulimit values

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL)

Issue

  • How to set ulimit values

Resolution

  • Settings in /etc/security/limits.conf take the following form:

    # vi /etc/security/limits.conf
#<domain>        <type>  <item>  <value>

*               -       core             <value>
*               -       data             <value>
*               -       priority         <value>
*               -       fsize            <value>
*               soft    sigpending       <value> eg:57344
*               hard    sigpending       <value> eg:57444
*               -       memlock          <value>
*               -       nofile           <value> eg:1024
*               -       msgqueue         <value> eg:819200
*               -       locks            <value>
*               soft    core             <value>
*               hard    nofile           <value>
@<group>        hard    nproc            <value>
<user>          soft    nproc            <value>
%<group>        hard    nproc            <value>
<user>          hard    nproc            <value>
@<group>        -       maxlogins        <value>
<user>          hard    cpu              <value>
<user>          soft    cpu              <value>
<user>          hard    locks            <value>

    • <domain> can be:

      • a user name
      • a group name, with @group syntax
      • the wildcard *, for default entry
      • the wildcard %, can be also used with %group syntax, for maxlogin limit

    • <type> can have two values:

      • soft for enforcing the soft limits
      • hard for enforcing hard limits
      • - for enforcing soft as well as hard limits

    • <item> can be one of the following:

      • core - limits the core file size (KB)
      • data - max data size (KB)
      • fsize - maximum filesize (KB)
      • memlock - max locked-in-memory address space (KB)
      • nofile - max number of open files
      • rss - max resident set size (KB)
      • stack - max stack size (KB)
      • cpu - max CPU time (MIN)
      • nproc - max number of processes (see note below)
      • as - address space limit (KB)
      • maxlogins - max number of logins for this user
      • maxsyslogins - max number of logins on the system
      • priority - the priority to run user process with
      • locks - max number of file locks the user can hold
      • sigpending - max number of pending signals
      • msgqueue - max memory used by POSIX message queues (bytes)
      • nice - max nice priority allowed to raise to values: [-20, 19]
      • rtprio - max realtime priority

  • Exit and re-login from the terminal for the change to take effect.

  • More details can be found from below command:

    # man limits.conf

  • Note that the nproc setting can no longer be set in limits.conf. Please use /etc/security/limits.d/90-nproc.conf instead. Setting nproc in /etc/security/limits.conf has no effect in Red Hat Enterprise Linux.

Diagnostic Steps

  • To improve performance, we can safely set the limit of processes for the super-user root to be unlimited. Edit the .bashrc file and add the following line:

    # vi /root/.bashrc
ulimit -u unlimited

  • Exit and re-login from the terminal for the change to take effect.

  • Can also run ulimit -u unlimited at the command prompt instead of adding it to the file /root/.bashrc.

This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.

Comments