man/runlevel.xml

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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="runlevel"
  25     xmlns:xi="http://www.w3.org/2001/XInclude"
  26     conditional="HAVE_UTMP">
  27
  28   <refentryinfo>
  29     <title>runlevel</title>
  30     <productname>systemd</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Lennart</firstname>
  36         <surname>Poettering</surname>
  37         <email>lennart@poettering.net</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>runlevel</refentrytitle>
  44     <manvolnum>8</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>runlevel</refname>
  49     <refpurpose>Print previous and current SysV runlevel</refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <cmdsynopsis>
  54       <command>runlevel</command>
  55       <arg choice="opt" rep="repeat">options</arg>
  56     </cmdsynopsis>
  57   </refsynopsisdiv>
  58
  59   <refsect1>
  60     <title>Overview</title>
  61
  62     <para>"Runlevels" are an obsolete way to start and stop groups of
  63     services used in SysV init. systemd provides a compatibility layer
  64     that maps runlevels to targets, and associated binaries like
  65     <command>runlevel</command>. Nevertheless, only one runlevel can
  66     be "active" at a given time, while systemd can activate multiple
  67     targets concurrently, so the mapping to runlevels is confusing
  68     and only approximate. Runlevels should not be used in new code,
  69     and are mostly useful as a shorthand way to refer the matching
  70     systemd targets in kernel boot parameters.</para>
  71
  72     <table>
  73       <title>Mapping between runlevels and systemd targets</title>
  74       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
  75         <colspec colname="runlevel" />
  76         <colspec colname="target" />
  77         <thead>
  78           <row>
  79             <entry>Runlevel</entry>
  80             <entry>Target</entry>
  81           </row>
  82         </thead>
  83         <tbody>
  84           <row>
  85             <entry>0</entry>
  86             <entry><filename>poweroff.target</filename></entry>
  87           </row>
  88           <row>
  89             <entry>1</entry>
  90             <entry><filename>rescue.target</filename></entry>
  91           </row>
  92           <row>
  93             <entry>2, 3, 4</entry>
  94             <entry><filename>multi-user.target</filename></entry>
  95           </row>
  96           <row>
  97             <entry>5</entry>
  98             <entry><filename>graphical.target</filename></entry>
  99           </row>
 100           <row>
 101             <entry>6</entry>
 102             <entry><filename>reboot.target</filename></entry>
 103           </row>
 104         </tbody>
 105       </tgroup>
 106     </table>
 107   </refsect1>
 108
 109   <refsect1>
 110     <title>Description</title>
 111
 112     <para><command>runlevel</command> prints the previous and current
 113     SysV runlevel if they are known.</para>
 114
 115     <para>The two runlevel characters are separated by a single space
 116     character. If a runlevel cannot be determined, N is printed
 117     instead. If neither can be determined, the word "unknown" is
 118     printed.</para>
 119
 120     <para>Unless overridden in the environment, this will check the
 121     utmp database for recent runlevel changes.</para>
 122   </refsect1>
 123
 124   <refsect1>
 125     <title>Options</title>
 126
 127     <para>The following option is understood:</para>
 128
 129     <variablelist>
 130       <varlistentry>
 131         <term><option>--help</option></term>
 132
 133         <xi:include href="standard-options.xml" xpointer="help-text" />
 134       </varlistentry>
 135     </variablelist>
 136
 137   </refsect1>
 138
 139   <refsect1>
 140     <title>Exit status</title>
 141
 142     <para>If one or both runlevels could be determined, 0 is returned,
 143     a non-zero failure code otherwise.</para>
 144
 145   </refsect1>
 146
 147   <refsect1>
 148     <title>Environment</title>
 149
 150     <variablelist class='environment-variables'>
 151       <varlistentry>
 152         <term><varname>$RUNLEVEL</varname></term>
 153
 154         <listitem><para>If <varname>$RUNLEVEL</varname> is set,
 155         <command>runlevel</command> will print this value as current
 156         runlevel and ignore utmp.</para></listitem>
 157       </varlistentry>
 158
 159       <varlistentry>
 160         <term><varname>$PREVLEVEL</varname></term>
 161
 162         <listitem><para>If <varname>$PREVLEVEL</varname> is set,
 163         <command>runlevel</command> will print this value as previous
 164         runlevel and ignore utmp.</para></listitem>
 165       </varlistentry>
 166     </variablelist>
 167   </refsect1>
 168
 169   <refsect1>
 170     <title>Files</title>
 171
 172     <variablelist>
 173       <varlistentry>
 174         <term><filename>/var/run/utmp</filename></term>
 175
 176         <listitem><para>The utmp database <command>runlevel</command>
 177         reads the previous and current runlevel
 178         from.</para></listitem>
 179       </varlistentry>
 180     </variablelist>
 181   </refsect1>
 182
 183   <refsect1>
 184     <title>See Also</title>
 185     <para>
 186       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 187       <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 188       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 189     </para>
 190   </refsect1>
 191
 192 </refentry>