shadow/man/limits.5.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
		"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
<refentry id='limits5'>
  <!-- $Id: limits.5.xml,v 1.6 2005/06/14 20:18:17 kloczek Exp $ -->
  <refmeta>
    <refentrytitle>LIMITS</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>
  <refnamediv id='name'>
    <refname>limits</refname>
    <refpurpose>Resource limits definition</refpurpose>
  </refnamediv>
  <!-- body begins here -->
  
  <refsect1 id='description'>
    <title>DESCRIPTION</title>
    <para>
      The <emphasis remap='I'>limits</emphasis> file (/etc/limits by
      default or LIMITS_FILE defined
      config.h) describes the resource limits you wish to impose. It
      should be
      owned by root and readable by root account only.
    </para>
    
    <para>By default no quotas are imposed on 'root'. In fact, there is no
      way to impose
      limits via this procedure to root-equiv accounts (accounts with UID
      0).
    </para>
    
    <para>Each line describes a limit for a user in the form:</para>
    
    <para>
      <emphasis remap='I'>user LIMITS_STRING</emphasis>
    </para>
    
    <para>
      The <emphasis remap='B'>LIMITS_STRING</emphasis> is a string of a
      concatenated list of resource limits.
      Each limit consists of a letter identifier followed by a numerical
      limit.
    </para>
    
    <para>The valid identifiers are:</para>
    
    <para>A: max address space (KB)
      <!-- .br -->
      C: max core file size (KB)
      <!-- .br -->
      D: max data size (KB)
      <!-- .br -->
      F: maximum filesize (KB)
      <!-- .br -->
      M: max locked-in-memory address space (KB)
      <!-- .br -->
      N: max number of open files
      <!-- .br -->
      R: max resident set size (KB)
      <!-- .br -->
      S: max stack size (KB)
      <!-- .br -->
      T: max CPU time (MIN)
      <!-- .br -->
      U: max number of processes
      <!-- .br -->
      K: file creation mask, set by 
      <citerefentry>
        <refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum>
      </citerefentry>
      .
      <!-- .br -->
      L: max number of logins for this user
      <!-- .br -->
      P: process priority, set by 
      <citerefentry>
        <refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum>
      </citerefentry>
      .
    </para>
    
    <para> For example, <emphasis remap='I'>L2D2048N5</emphasis> is a valid
      <emphasis remap='B'>LIMITS_STRING </emphasis>. For reading
      convenience, the following entries are equivalent:
    </para>
    
    <para>username L2D2048N5
      <!-- .br -->
      username L2 D2048 N5
    </para>
    
    <para> Be aware that after <emphasis remap='I'>username</emphasis> the
      rest of the line is considered a limit string, thus comments are not
      allowed. A invalid limits string will be rejected (not considered) by
      the login program.
    </para>
    
    <para> The default entry is denoted by username "<emphasis
      remap='B'>*</emphasis>". If you have multiple <emphasis
      remap='I'>default</emphasis> entries in your <emphasis
      remap='B'>LIMITS_FILE</emphasis>, then the last one will be used as
      the default entry.
    </para>
    
    <para>To completely disable limits for a user, a single dash "<emphasis
      remap='B'>-</emphasis> "will do.
    </para>
    
    <para>Also, please note that all limit settings are set PER LOGIN. They
      are not global, nor are they permanent. Perhaps global limits will
      come, but for now this will have to do ;)
    </para>
  </refsect1>
  
  <refsect1 id='files'>
    <title>FILES</title>
    <variablelist>
      <varlistentry>
        <term><filename>/etc/limits</filename></term>
        <listitem></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  
  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para><citerefentry>
        <refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
  
  <refsect1 id='author'>
    <title>AUTHOR</title>
    <para>Cristian Gafton (gafton@sorosis.ro)</para>
  </refsect1>
</refentry>