man/systemd.special.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">
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   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU General Public License as published by
  12   the Free Software Foundation; either version 2 of the License, or
  13   (at your option) any later version.
  14
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  18   General Public License for more details.
  19
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  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
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  23
  24 <refentry id="systemd.special">
  25
  26         <refentryinfo>
  27                 <title>systemd.special</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd.special</refentrytitle>
  42                 <manvolnum>7</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.special</refname>
  47                 <refpurpose>special systemd units</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename>emergency.service</filename></para>
  52                 <para><filename>local-fs.target</filename></para>
  53                 <para><filename>network.target</filename></para>
  54                 <para><filename>nss-lookup.target</filename></para>
  55                 <para><filename>remote-fs.target</filename></para>
  56                 <para><filename>rpcbind.target</filename></para>
  57                 <para><filename>rtc-set.target</filename></para>
  58                 <para><filename>shutdown.target</filename></para>
  59                 <para><filename>sigpwr.target</filename></para>
  60                 <para><filename>sockets.target</filename></para>
  61                 <para><filename>swap.target</filename></para>
  62                 <para><filename>syslog.target</filename></para>
  63                 <para><filename>systemd-initctl.service</filename></para>
  64                 <para><filename>systemd-initctl.socket</filename></para>
  65                 <para><filename>systemd-logger.service</filename></para>
  66                 <para><filename>systemd-logger.socket</filename></para>
  67         </refsynopsisdiv>
  68
  69         <refsect1>
  70                 <title>Description</title>
  71
  72                 <para>A few units are treated specially by
  73                 systemd. They have special internal semantics and
  74                 cannot be renamed.</para>
  75         </refsect1>
  76
  77         <refsect1>
  78                 <title>Special System Units</title>
  79
  80                 <variablelist>
  81                         <varlistentry>
  82                                 <term><filename>emergency.service</filename></term>
  83                                 <listitem>
  84                                         <para>A special service unit
  85                                         that starts an emergency
  86                                         shell on the main
  87                                         console. This unit is supposed
  88                                         to be used with the kernel
  89                                         command line option
  90                                         <varname>systemd.default=</varname>
  91                                         and has otherwise little use.
  92                                         </para>
  93                                 </listitem>
  94                         </varlistentry>
  95                         <varlistentry>
  96                                 <term><filename>local-fs.target</filename></term>
  97                                 <listitem>
  98                                         <para>systemd automatically
  99                                         adds dependencies of type
 100                                         After to all mount units that
 101                                         refer to local mount
 102                                         points. In addition, systemd
 103                                         adds dependencies of type
 104                                         Wants to those mounts listed
 105                                         in
 106                                         <filename>/etc/fstab</filename>
 107                                         that have the
 108                                         <literal>auto</literal> and
 109                                         <literal>comment=systemd.mount</literal>
 110                                         mount options set.</para>
 111
 112                                         <para>systemd automatically
 113                                         adds dependencies of type
 114                                         After to this target unit for
 115                                         all SysV init scripts with an
 116                                         LSB header referring to the
 117                                         <literal>$local_fs</literal>
 118                                         facility.</para>
 119                                 </listitem>
 120                         </varlistentry>
 121                         <varlistentry>
 122                                 <term><filename>network.target</filename></term>
 123                                 <listitem>
 124                                         <para>systemd automatically
 125                                         adds dependencies of type
 126                                         After to this target unit for
 127                                         all SysV init scripts with an
 128                                         LSB header referring to the
 129                                         <literal>$network</literal>
 130                                         facility.</para>
 131                                 </listitem>
 132                         </varlistentry>
 133                         <varlistentry>
 134                                 <term><filename>nss-lookup.target</filename></term>
 135                                 <listitem>
 136                                         <para>systemd automatically
 137                                         adds dependencies of type
 138                                         After to this target unit for
 139                                         all SysV init scripts with an
 140                                         LSB header referring to the
 141                                         <literal>$named</literal>
 142                                         facility.</para>
 143                                 </listitem>
 144                         </varlistentry>
 145                         <varlistentry>
 146                                 <term><filename>remote-fs.target</filename></term>
 147                                 <listitem>
 148                                         <para>Similar to <filename>local-fs.target</filename>, but for remote mount points.</para>
 149                                         <para>systemd automatically
 150                                         adds dependencies of type
 151                                         After to this target unit for
 152                                         all SysV init scripts with an
 153                                         LSB header referring to the
 154                                         <literal>$remote-fs</literal>
 155                                         facility.</para>
 156                                 </listitem>
 157                         </varlistentry>
 158                         <varlistentry>
 159                                 <term><filename>rpcbind.target</filename></term>
 160                                 <listitem>
 161                                         <para>systemd automatically
 162                                         adds dependencies of type
 163                                         After to this target unit for
 164                                         all SysV init scripts with an
 165                                         LSB header referring to the
 166                                         <literal>$rpcbind</literal>
 167                                         facility.</para>
 168                                 </listitem>
 169                         </varlistentry>
 170                         <varlistentry>
 171                                 <term><filename>rtc-set.target</filename></term>
 172                                 <listitem>
 173                                         <para>systemd automatically
 174                                         adds dependencies of type
 175                                         After to this target unit for
 176                                         all SysV init scripts with an
 177                                         LSB header referring to the
 178                                         <literal>$time</literal>
 179                                         facility.</para>
 180                                 </listitem>
 181                         </varlistentry>
 182                         <varlistentry>
 183                                 <term><filename>shutdown.target</filename></term>
 184                                 <listitem>
 185                                         <para>A special target unit
 186                                         that terminates the services
 187                                         on system shutdown.</para>
 188
 189                                         <para>Services that shall be
 190                                         terminated on system shutdown
 191                                         shall add Wants dependencies
 192                                         from this unit to their
 193                                         service unit during
 194                                         installation.</para>
 195
 196                                         <para>systemd automatically
 197                                         adds dependencies of type
 198                                         Conflicts to this target unit
 199                                         for all SysV init scripts that
 200                                         shall be terminated in SysV
 201                                         runlevels 0 or 6.</para>
 202                                 </listitem>
 203                         </varlistentry>
 204                         <varlistentry>
 205                                 <term><filename>sigpwr.target</filename></term>
 206                                 <listitem>
 207                                         <para>A special target that is
 208                                         started when systemd receives
 209                                         the SIGPWR process signal,
 210                                         which is normally sent by the
 211                                         kernel or UPS daemons when the
 212                                         power fails.</para>
 213                                 </listitem>
 214                         </varlistentry>
 215                         <varlistentry>
 216                                 <term><filename>sockets.target</filename></term>
 217                                 <listitem>
 218                                         <para>A special target unit
 219                                         that sets up all service
 220                                         sockets.</para>
 221
 222                                         <para>Services that can be
 223                                         socket-activated shall add
 224                                         Wants dependencies from this
 225                                         unit to their socket unit
 226                                         during installation.</para>
 227                                 </listitem>
 228                         </varlistentry>
 229                         <varlistentry>
 230                                 <term><filename>swap.target</filename></term>
 231                                 <listitem>
 232                                         <para>Similar to
 233                                         <filename>local-fs.target</filename>, but for swap
 234                                         partitions and swap
 235                                         files.</para>
 236                                 </listitem>
 237                         </varlistentry>
 238                         <varlistentry>
 239                                 <term><filename>syslog.target</filename></term>
 240                                 <listitem>
 241                                         <para>systemd automatically
 242                                         adds dependencies of type
 243                                         After to this target unit for
 244                                         all SysV init scripts with an
 245                                         LSB header referring to the
 246                                         <literal>$syslog</literal>
 247                                         facility.</para>
 248
 249                                         <para>Administrators should
 250                                         ensure that this target pulls
 251                                         in a service unit with the
 252                                         name or alias of
 253                                         <filename>@SPECIAL_SYSLOG_NAME@</filename> (or a
 254                                         socket unit that activates
 255                                         this service).</para>
 256                                 </listitem>
 257                         </varlistentry>
 258                         <varlistentry>
 259                                 <term><filename>systemd-initctl.service</filename></term>
 260                                 <listitem>
 261                                         <para>This provides
 262                                         compatibility with the SysV
 263                                         /dev/initctl file system FIFO
 264                                         for communication with the
 265                                         init system.</para>
 266                                         <para>This is a
 267                                         socket-activated service, see
 268                                         <filename>system-initctl.socket</filename>.</para>
 269                                 </listitem>
 270                         </varlistentry>
 271                         <varlistentry>
 272                                 <term><filename>systemd-initctl.socket</filename></term>
 273                                 <listitem>
 274                                         <para>Socket activation unit
 275                                         for
 276                                         <filename>system-initctl.service</filename>.</para>
 277                                 </listitem>
 278                         </varlistentry>
 279                         <varlistentry>
 280                                 <term><filename>systemd-logger.service</filename></term>
 281                                 <listitem>
 282                                         <para>This is used internally
 283                                         by systemd to provide syslog
 284                                         logging to started
 285                                         processes.</para>
 286                                         <para>This is a
 287                                         socket-activated service, see
 288                                         <filename>system-logger.socket</filename>.</para>
 289                                 </listitem>
 290                         </varlistentry>
 291                         <varlistentry>
 292                                 <term><filename>systemd-logger.socket</filename></term>
 293                                 <listitem>
 294                                         <para>Socket activation unit
 295                                         for
 296                                         <filename>system-logger.service</filename>.</para>
 297                                 </listitem>
 298                         </varlistentry>
 299                 </variablelist>
 300         </refsect1>
 301
 302         <refsect1>
 303                 <title>Special Session Units</title>
 304
 305                 <para>When systemd runs as a service instance, the
 306                 following special units are available, which have
 307                 similar definitions as their system counterparts:
 308                 <filename>local-fs.target</filename>,
 309                 <filename>remote-fs.target</filename>,
 310                 <filename>shutdown.target</filename>,
 311                 <filename>sockets.target</filename>,
 312                 <filename>swap.target</filename>.</para>
 313         </refsect1>
 314
 315         <refsect1>
 316                   <title>See Also</title>
 317                   <para>
 318                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 319                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 320                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 321                           <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 322                   </para>
 323         </refsect1>
 324
 325 </refentry>