man/runlevel.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright 2010 Lennart Poettering
   9 -->
  10
  11 <refentry id="runlevel"
  12     xmlns:xi="http://www.w3.org/2001/XInclude"
  13     conditional="ENABLE_UTMP">
  14
  15   <refentryinfo>
  16     <title>runlevel</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>Developer</contrib>
  22         <firstname>Lennart</firstname>
  23         <surname>Poettering</surname>
  24         <email>lennart@poettering.net</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>runlevel</refentrytitle>
  31     <manvolnum>8</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>runlevel</refname>
  36     <refpurpose>Print previous and current SysV runlevel</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <cmdsynopsis>
  41       <command>runlevel</command>
  42       <arg choice="opt" rep="repeat">options</arg>
  43     </cmdsynopsis>
  44   </refsynopsisdiv>
  45
  46   <refsect1>
  47     <title>Overview</title>
  48
  49     <para>"Runlevels" are an obsolete way to start and stop groups of
  50     services used in SysV init. systemd provides a compatibility layer
  51     that maps runlevels to targets, and associated binaries like
  52     <command>runlevel</command>. Nevertheless, only one runlevel can
  53     be "active" at a given time, while systemd can activate multiple
  54     targets concurrently, so the mapping to runlevels is confusing
  55     and only approximate. Runlevels should not be used in new code,
  56     and are mostly useful as a shorthand way to refer the matching
  57     systemd targets in kernel boot parameters.</para>
  58
  59     <table>
  60       <title>Mapping between runlevels and systemd targets</title>
  61       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
  62         <colspec colname="runlevel" />
  63         <colspec colname="target" />
  64         <thead>
  65           <row>
  66             <entry>Runlevel</entry>
  67             <entry>Target</entry>
  68           </row>
  69         </thead>
  70         <tbody>
  71           <row>
  72             <entry>0</entry>
  73             <entry><filename>poweroff.target</filename></entry>
  74           </row>
  75           <row>
  76             <entry>1</entry>
  77             <entry><filename>rescue.target</filename></entry>
  78           </row>
  79           <row>
  80             <entry>2, 3, 4</entry>
  81             <entry><filename>multi-user.target</filename></entry>
  82           </row>
  83           <row>
  84             <entry>5</entry>
  85             <entry><filename>graphical.target</filename></entry>
  86           </row>
  87           <row>
  88             <entry>6</entry>
  89             <entry><filename>reboot.target</filename></entry>
  90           </row>
  91         </tbody>
  92       </tgroup>
  93     </table>
  94   </refsect1>
  95
  96   <refsect1>
  97     <title>Description</title>
  98
  99     <para><command>runlevel</command> prints the previous and current
 100     SysV runlevel if they are known.</para>
 101
 102     <para>The two runlevel characters are separated by a single space
 103     character. If a runlevel cannot be determined, N is printed
 104     instead. If neither can be determined, the word "unknown" is
 105     printed.</para>
 106
 107     <para>Unless overridden in the environment, this will check the
 108     utmp database for recent runlevel changes.</para>
 109   </refsect1>
 110
 111   <refsect1>
 112     <title>Options</title>
 113
 114     <para>The following option is understood:</para>
 115
 116     <variablelist>
 117       <varlistentry>
 118         <term><option>--help</option></term>
 119
 120         <xi:include href="standard-options.xml" xpointer="help-text" />
 121       </varlistentry>
 122     </variablelist>
 123
 124   </refsect1>
 125
 126   <refsect1>
 127     <title>Exit status</title>
 128
 129     <para>If one or both runlevels could be determined, 0 is returned,
 130     a non-zero failure code otherwise.</para>
 131
 132   </refsect1>
 133
 134   <refsect1>
 135     <title>Environment</title>
 136
 137     <variablelist class='environment-variables'>
 138       <varlistentry>
 139         <term><varname>$RUNLEVEL</varname></term>
 140
 141         <listitem><para>If <varname>$RUNLEVEL</varname> is set,
 142         <command>runlevel</command> will print this value as current
 143         runlevel and ignore utmp.</para></listitem>
 144       </varlistentry>
 145
 146       <varlistentry>
 147         <term><varname>$PREVLEVEL</varname></term>
 148
 149         <listitem><para>If <varname>$PREVLEVEL</varname> is set,
 150         <command>runlevel</command> will print this value as previous
 151         runlevel and ignore utmp.</para></listitem>
 152       </varlistentry>
 153     </variablelist>
 154   </refsect1>
 155
 156   <refsect1>
 157     <title>Files</title>
 158
 159     <variablelist>
 160       <varlistentry>
 161         <term><filename>/run/utmp</filename></term>
 162
 163         <listitem><para>The utmp database <command>runlevel</command> reads the previous and current runlevel
 164         from.</para></listitem>
 165       </varlistentry>
 166     </variablelist>
 167   </refsect1>
 168
 169   <refsect1>
 170     <title>See Also</title>
 171     <para>
 172       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 173       <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 174       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 175     </para>
 176   </refsect1>
 177
 178 </refentry>