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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.conf">
+
+ <refmeta>
+ <refentrytitle>limits.conf</refentrytitle>
+ <manvolnum>5</manvolnum>
+ <refmiscinfo class="sectdesc">Linux-PAM Manual</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+ <refname>limits.conf</refname>
+ <refpurpose>configuration file for the pam_limits module</refpurpose>
+ </refnamediv>
+
+ <refsect1 id='limits.conf-description'>
+ <title>DESCRIPTION</title>
+ <para>
+ The <emphasis>pam_limits.so</emphasis> module applies ulimit limits,
+ nice priority and number of simultaneous login sessions limit to user
+ login sessions. This description of the configuration file syntax
+ applies to the <filename>/etc/security/limits.conf</filename> file and
+ <filename>*.conf</filename> files in the
+ <filename>/etc/security/limits.d</filename> directory.
+ </para>
+ <para>
+ The syntax of the lines is as follows:
+ </para>
+ <para>
+ <replaceable>&lt;domain&gt;</replaceable> <replaceable>&lt;type&gt;</replaceable>
+ <replaceable>&lt;item&gt;</replaceable> <replaceable>&lt;value&gt;</replaceable>
+ </para>
+ <para>
+ The fields listed above should be filled as follows:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>&lt;domain&gt;</option>
+ </term>
+ <listitem>
+ <itemizedlist>
+ <listitem>
+ <para>
+ a username
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ a groupname, with <emphasis remap='B'>@group</emphasis> syntax.
+ This should not be confused with netgroups.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ the wildcard <emphasis remap='B'>*</emphasis>, for default entry.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ the wildcard <emphasis remap='B'>%</emphasis>, for maxlogins limit only,
+ can also be used with <emphasis remap='B'>%group</emphasis> syntax. If the
+ <emphasis remap='B'>%</emphasis> wildcard is used alone it is identical
+ to using <emphasis remap='B'>*</emphasis> with maxsyslogins limit. With
+ a group specified after <emphasis remap='B'>%</emphasis> it limits the total
+ number of logins of all users that are member of the group.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ an uid range specified as <replaceable>&lt;min_uid&gt;</replaceable><emphasis
+ remap='B'>:</emphasis><replaceable>&lt;max_uid&gt;</replaceable>. If min_uid
+ is omitted, the match is exact for the max_uid. If max_uid is omitted, all
+ uids greater than or equal min_uid match.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ a gid range specified as <emphasis
+ remap='B'>@</emphasis><replaceable>&lt;min_gid&gt;</replaceable><emphasis
+ remap='B'>:</emphasis><replaceable>&lt;max_gid&gt;</replaceable>. If min_gid
+ is omitted, the match is exact for the max_gid. If max_gid is omitted, all
+ gids greater than or equal min_gid match. For the exact match all groups including
+ the user's supplementary groups are examined. For the range matches only
+ the user's primary group is examined.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ a gid specified as <emphasis
+ remap='B'>%:</emphasis><replaceable>&lt;gid&gt;</replaceable> applicable
+ to maxlogins limit only. It limits the total number of logins of all users
+ that are member of the group with the specified gid.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>&lt;type&gt;</option>
+ </term>
+ <listitem>
+ <variablelist>
+ <varlistentry>
+ <term><option>hard</option></term>
+ <listitem>
+ <para>
+ for enforcing <emphasis remap='B'>hard</emphasis> resource limits.
+ These limits are set by the superuser and enforced by the Kernel.
+ The user cannot raise his requirement of system resources above such values.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>soft</option></term>
+ <listitem>
+ <para>
+ for enforcing <emphasis remap='B'>soft</emphasis> resource limits.
+ These limits are ones that the user can move up or down within the
+ permitted range by any pre-existing <emphasis remap='B'>hard</emphasis>
+ limits. The values specified with this token can be thought of as
+ <emphasis>default</emphasis> values, for normal system usage.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-</option></term>
+ <listitem>
+ <para>
+ for enforcing both <emphasis remap='B'>soft</emphasis> and
+ <emphasis remap='B'>hard</emphasis> resource limits together.
+ </para>
+ <para>
+ Note, if you specify a type of '-' but neglect to supply the
+ item and value fields then the module will never enforce any
+ limits on the specified user/group etc. .
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>&lt;item&gt;</option>
+ </term>
+ <listitem>
+ <variablelist>
+ <varlistentry>
+ <term><option>core</option></term>
+ <listitem>
+ <para>limits the core file size (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>data</option></term>
+ <listitem>
+ <para>maximum data size (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>fsize</option></term>
+ <listitem>
+ <para>maximum filesize (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>memlock</option></term>
+ <listitem>
+ <para>maximum locked-in-memory address space (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>nofile</option></term>
+ <listitem>
+ <para>maximum number of open file descriptors</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>rss</option></term>
+ <listitem>
+ <para>maximum resident set size (KB) (Ignored in Linux 2.4.30 and higher)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>stack</option></term>
+ <listitem>
+ <para>maximum stack size (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>cpu</option></term>
+ <listitem>
+ <para>maximum CPU time (minutes)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>nproc</option></term>
+ <listitem>
+ <para>maximum number of processes</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>as</option></term>
+ <listitem>
+ <para>address space limit (KB)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>maxlogins</option></term>
+ <listitem>
+ <para>maximum number of logins for this user (this limit does
+ not apply to user with <emphasis>uid=0</emphasis>)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>maxsyslogins</option></term>
+ <listitem>
+ <para>maximum number of all logins on system; user is not
+ allowed to log-in if total number of all user logins is
+ greater than specified number (this limit does not apply to
+ user with <emphasis>uid=0</emphasis>)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>nonewprivs</option></term>
+ <listitem>
+ <para>value of 0 or 1; if set to 1 disables acquiring new
+ privileges by invoking prctl(PR_SET_NO_NEW_PRIVS)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>priority</option></term>
+ <listitem>
+ <para>the priority to run user process with (negative
+ values boost process priority)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>locks</option></term>
+ <listitem>
+ <para>maximum locked files (Linux 2.4 and higher)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>sigpending</option></term>
+ <listitem>
+ <para>maximum number of pending signals (Linux 2.6 and higher)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>msgqueue</option></term>
+ <listitem>
+ <para>maximum memory used by POSIX message queues (bytes)
+ (Linux 2.6 and higher)</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>nice</option></term>
+ <listitem>
+ <para>maximum nice priority allowed to raise to (Linux 2.6.12 and higher) values: [-20,19]</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>rtprio</option></term>
+ <listitem>
+ <para>maximum realtime priority allowed for non-privileged processes
+ (Linux 2.6.12 and higher)</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+
+ </variablelist>
+ <para>
+ All items support the values <emphasis>-1</emphasis>,
+ <emphasis>unlimited</emphasis> or <emphasis>infinity</emphasis> indicating no limit,
+ except for <emphasis remap='B'>priority</emphasis>, <emphasis remap='B'>nice</emphasis>,
+ and <emphasis remap='B'>nonewprivs</emphasis>.
+ If <emphasis remap='B'>nofile</emphasis> is to be set to one of these values,
+ it will be set to the contents of /proc/sys/fs/nr_open instead (see setrlimit(3)).
+ </para>
+ <para>
+ If a hard limit or soft limit of a resource is set to a valid value,
+ but outside of the supported range of the local system, the system
+ may reject the new limit or unexpected behavior may occur. If the
+ control value <emphasis>required</emphasis> is used, the module will
+ reject the login if a limit could not be set.
+ </para>
+ <para>
+ In general, individual limits have priority over group limits, so if
+ you impose no limits for <emphasis>admin</emphasis> group, but one of
+ the members in this group have a limits line, the user will have its
+ limits set according to this line.
+ </para>
+ <para>
+ Also, please note that all limit settings are set
+ <emphasis>per login</emphasis>. They are not global, nor are they
+ permanent; existing only for the duration of the session.
+ One exception is the <emphasis>maxlogin</emphasis> option, this one
+ is system wide. But there is a race, concurrent logins at the same
+ time will not always be detect as such but only counted as one.
+ </para>
+ <para>
+ In the <emphasis>limits</emphasis> configuration file, the
+ '<emphasis remap='B'>#</emphasis>' character introduces a comment
+ - after which the rest of the line is ignored.
+ </para>
+ <para>
+ The pam_limits module does report configuration problems
+ found in its configuration file and errors via <citerefentry>
+ <refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ </para>
+ </refsect1>
+
+ <refsect1 id="limits.conf-examples">
+ <title>EXAMPLES</title>
+ <para>
+ These are some example lines which might be specified in
+ <filename>/etc/security/limits.conf</filename>.
+ </para>
+ <programlisting>
+* soft core 0
+* hard nofile 512
+@student hard nproc 20
+@faculty soft nproc 20
+@faculty hard nproc 50
+ftp hard nproc 0
+@student - maxlogins 4
+@student - nonewprivs 1
+:123 hard cpu 5000
+@500: soft cpu 10000
+600:700 hard locks 10
+ </programlisting>
+ </refsect1>
+
+ <refsect1 id="limits.conf-see_also">
+ <title>SEE ALSO</title>
+ <para>
+ <citerefentry><refentrytitle>pam_limits</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>getrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>getrlimit</refentrytitle><manvolnum>3p</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+ <refsect1 id="limits.conf-author">
+ <title>AUTHOR</title>
+ <para>
+ pam_limits was initially written by Cristian Gafton &lt;gafton@redhat.com&gt;
+ </para>
+ </refsect1>
+</refentry>