shadow/man/limits.5.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
<refentry id='limits.5'>
<!-- $Id: limits.5.xml,v 1.17 2005/11/05 17:17:29 kloczek Exp $ -->
<refmeta>
<refentrytitle>limits</refentrytitle>
<manvolnum>5</manvolnum>
<refmiscinfo class="sectdesc">File Formats and Conversions</refmiscinfo>
</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 quota is 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>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>
<itemizedlist>
<listitem><para>A: max address space (KB)</para></listitem>
<listitem><para>C: max core file size (KB)</para></listitem>
<listitem><para>D: max data size (KB)</para></listitem>
<listitem><para>F: maximum filesize (KB)</para></listitem>
<listitem><para>M: max locked-in-memory address space (KB)</para></listitem>
<listitem><para>N: max number of open files</para></listitem>
<listitem><para>R: max resident set size (KB)</para></listitem>
<listitem><para>S: max stack size (KB)</para></listitem>
<listitem><para>T: max CPU time (MIN)</para></listitem>
<listitem><para>U: max number of processes</para></listitem>
<listitem><para>K: file creation mask, set by
<citerefentry>
<refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum>
</citerefentry>.</para>
</listitem>
<listitem><para>L: max number of logins for this user</para></listitem>
<listitem><para>P: process priority, set by
<citerefentry>
<refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum>
</citerefentry>.</para>
</listitem>
</itemizedlist>
<para>
For example, <emphasis remap='I'>L2D2048N5</emphasis> is a valid
<emphasis>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>*</emphasis>". If
you have multiple <emphasis remap='I'>default</emphasis> entries in
your <emphasis>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>-</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><para></para></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>
</refentry>