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<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright (c) 1997 , Luca Berra
Copyright (c) 2001 - 2007, Tomasz Kłoczko
Copyright (c) 2005 - 2006, Yuri Kozlov
Copyright (c) 2005 - 2008, Nicolas François
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the copyright holders or contributors may not be used to
endorse or promote products derived from this software without
specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!-- SHADOW-CONFIG-HERE -->
]>
<refentry id='limits.5'>
<!-- $Id$ -->
<refentryinfo>
<author>
<firstname>Luca</firstname>
<surname>Berra</surname>
<contrib>Creation, 1997</contrib>
</author>
<author>
<firstname>Thomas</firstname>
<surname>Kłoczko</surname>
<email>kloczek@pld.org.pl</email>
<contrib>shadow-utils maintainer, 2000 - 2007</contrib>
</author>
<author>
<firstname>Nicolas</firstname>
<surname>François</surname>
<email>nicolas.francois@centraliens.net</email>
<contrib>shadow-utils maintainer, 2007 - now</contrib>
</author>
</refentryinfo>
<refmeta>
<refentrytitle>limits</refentrytitle>
<manvolnum>5</manvolnum>
<refmiscinfo class="sectdesc">File Formats and Conversions</refmiscinfo>
<refmiscinfo class="source">shadow-utils</refmiscinfo>
<refmiscinfo class="version">&SHADOW_UTILS_VERSION;</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
(<filename>/etc/limits</filename> by default
or LIMITS_FILE defined <filename>config.h</filename>) 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>or in the form:</para>
<para>
<emphasis remap='I'>@group 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 file size (KB)</para></listitem>
<listitem><para>K: file creation mask, set by
<citerefentry>
<refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum>
</citerefentry>.</para>
</listitem>
<listitem><para>I: max nice value (0..39 which translates to
20..-19)</para></listitem>
<listitem><para>L: max number of logins for this user</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>O: max real time priority</para></listitem>
<listitem><para>P: process priority, set by
<citerefentry>
<refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum>
</citerefentry>.</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>
</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>
<programlisting>
username L2D2048N5
username L2 D2048 N5
</programlisting>
<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. An invalid limits string will be rejected (not considered) by
the <command>login</command> 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>
The limits specified in the form "<replaceable>@group</replaceable>"
apply to the members of the specified
<replaceable>group</replaceable>.
</para>
<para>
If more than one line with limits for a user exist, only the first line for
this user will be considered.
</para>
<para>
If no lines are specified for a user, the last
<replaceable>@group</replaceable> line matching a group whose the
user is a member of will be considered, or the last line with
default limits if no groups contain the user.
</para>
<para>
To completely disable limits for a user, a single dash
"<emphasis>-</emphasis>" will do.
</para>
<para>
To disable a limit for a user, a single dash
"<replaceable>-</replaceable>" can be used instead of the numerical
value for this limit.
</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>
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