man/runlevel.xml

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  10   Copyright 2010 Lennart Poettering
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  25
  26 <refentry id="runlevel"
  27     xmlns:xi="http://www.w3.org/2001/XInclude"
  28     conditional="ENABLE_UTMP">
  29
  30   <refentryinfo>
  31     <title>runlevel</title>
  32     <productname>systemd</productname>
  33
  34     <authorgroup>
  35       <author>
  36         <contrib>Developer</contrib>
  37         <firstname>Lennart</firstname>
  38         <surname>Poettering</surname>
  39         <email>lennart@poettering.net</email>
  40       </author>
  41     </authorgroup>
  42   </refentryinfo>
  43
  44   <refmeta>
  45     <refentrytitle>runlevel</refentrytitle>
  46     <manvolnum>8</manvolnum>
  47   </refmeta>
  48
  49   <refnamediv>
  50     <refname>runlevel</refname>
  51     <refpurpose>Print previous and current SysV runlevel</refpurpose>
  52   </refnamediv>
  53
  54   <refsynopsisdiv>
  55     <cmdsynopsis>
  56       <command>runlevel</command>
  57       <arg choice="opt" rep="repeat">options</arg>
  58     </cmdsynopsis>
  59   </refsynopsisdiv>
  60
  61   <refsect1>
  62     <title>Overview</title>
  63
  64     <para>"Runlevels" are an obsolete way to start and stop groups of
  65     services used in SysV init. systemd provides a compatibility layer
  66     that maps runlevels to targets, and associated binaries like
  67     <command>runlevel</command>. Nevertheless, only one runlevel can
  68     be "active" at a given time, while systemd can activate multiple
  69     targets concurrently, so the mapping to runlevels is confusing
  70     and only approximate. Runlevels should not be used in new code,
  71     and are mostly useful as a shorthand way to refer the matching
  72     systemd targets in kernel boot parameters.</para>
  73
  74     <table>
  75       <title>Mapping between runlevels and systemd targets</title>
  76       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
  77         <colspec colname="runlevel" />
  78         <colspec colname="target" />
  79         <thead>
  80           <row>
  81             <entry>Runlevel</entry>
  82             <entry>Target</entry>
  83           </row>
  84         </thead>
  85         <tbody>
  86           <row>
  87             <entry>0</entry>
  88             <entry><filename>poweroff.target</filename></entry>
  89           </row>
  90           <row>
  91             <entry>1</entry>
  92             <entry><filename>rescue.target</filename></entry>
  93           </row>
  94           <row>
  95             <entry>2, 3, 4</entry>
  96             <entry><filename>multi-user.target</filename></entry>
  97           </row>
  98           <row>
  99             <entry>5</entry>
 100             <entry><filename>graphical.target</filename></entry>
 101           </row>
 102           <row>
 103             <entry>6</entry>
 104             <entry><filename>reboot.target</filename></entry>
 105           </row>
 106         </tbody>
 107       </tgroup>
 108     </table>
 109   </refsect1>
 110
 111   <refsect1>
 112     <title>Description</title>
 113
 114     <para><command>runlevel</command> prints the previous and current
 115     SysV runlevel if they are known.</para>
 116
 117     <para>The two runlevel characters are separated by a single space
 118     character. If a runlevel cannot be determined, N is printed
 119     instead. If neither can be determined, the word "unknown" is
 120     printed.</para>
 121
 122     <para>Unless overridden in the environment, this will check the
 123     utmp database for recent runlevel changes.</para>
 124   </refsect1>
 125
 126   <refsect1>
 127     <title>Options</title>
 128
 129     <para>The following option is understood:</para>
 130
 131     <variablelist>
 132       <varlistentry>
 133         <term><option>--help</option></term>
 134
 135         <xi:include href="standard-options.xml" xpointer="help-text" />
 136       </varlistentry>
 137     </variablelist>
 138
 139   </refsect1>
 140
 141   <refsect1>
 142     <title>Exit status</title>
 143
 144     <para>If one or both runlevels could be determined, 0 is returned,
 145     a non-zero failure code otherwise.</para>
 146
 147   </refsect1>
 148
 149   <refsect1>
 150     <title>Environment</title>
 151
 152     <variablelist class='environment-variables'>
 153       <varlistentry>
 154         <term><varname>$RUNLEVEL</varname></term>
 155
 156         <listitem><para>If <varname>$RUNLEVEL</varname> is set,
 157         <command>runlevel</command> will print this value as current
 158         runlevel and ignore utmp.</para></listitem>
 159       </varlistentry>
 160
 161       <varlistentry>
 162         <term><varname>$PREVLEVEL</varname></term>
 163
 164         <listitem><para>If <varname>$PREVLEVEL</varname> is set,
 165         <command>runlevel</command> will print this value as previous
 166         runlevel and ignore utmp.</para></listitem>
 167       </varlistentry>
 168     </variablelist>
 169   </refsect1>
 170
 171   <refsect1>
 172     <title>Files</title>
 173
 174     <variablelist>
 175       <varlistentry>
 176         <term><filename>/run/utmp</filename></term>
 177
 178         <listitem><para>The utmp database <command>runlevel</command> reads the previous and current runlevel
 179         from.</para></listitem>
 180       </varlistentry>
 181     </variablelist>
 182   </refsect1>
 183
 184   <refsect1>
 185     <title>See Also</title>
 186     <para>
 187       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 188       <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 189       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 190     </para>
 191   </refsect1>
 192
 193 </refentry>