projects / thirdparty / systemd.git / blame
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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
| 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
| 12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| 9f235308 LP |
4 | |
| 5 | <!-- | |
| 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 | |
| 5430f7f2 LP |
11 | under the terms of the GNU Lesser General Public License as published by |
| 12 | the Free Software Foundation; either version 2.1 of the License, or | |
| 9f235308 LP |
13 | (at your option) any later version. |
| 14 | ||
| 15 | systemd is distributed in the hope that it will be useful, but | |
| 16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 5430f7f2 | 18 | Lesser General Public License for more details. |
| 9f235308 | 19 | |
| 5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
| 9f235308 LP |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| 22 | --> | |
| 23 | ||
| 24 | <refentry id="systemd.special"> | |
| 25 | ||
| 798d3a52 ZJS |
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>basic.target</filename>, | |
| 52 | <filename>bluetooth.target</filename>, | |
| 53 | <filename>ctrl-alt-del.target</filename>, | |
| 54 | <filename>cryptsetup.target</filename>, | |
| 55 | <filename>cryptsetup-pre.target</filename>, | |
| 56 | <filename>dbus.service</filename>, | |
| 57 | <filename>dbus.socket</filename>, | |
| 58 | <filename>default.target</filename>, | |
| 59 | <filename>display-manager.service</filename>, | |
| 60 | <filename>emergency.target</filename>, | |
| 61 | <filename>exit.target</filename>, | |
| 62 | <filename>final.target</filename>, | |
| 63 | <filename>getty.target</filename>, | |
| 64 | <filename>graphical.target</filename>, | |
| 65 | <filename>halt.target</filename>, | |
| 66 | <filename>hibernate.target</filename>, | |
| 67 | <filename>hybrid-sleep.target</filename>, | |
| 68 | <filename>initrd-fs.target</filename>, | |
| 69 | <filename>kbrequest.target</filename>, | |
| 70 | <filename>kexec.target</filename>, | |
| 71 | <filename>local-fs.target</filename>, | |
| 72 | <filename>local-fs-pre.target</filename>, | |
| 73 | <filename>multi-user.target</filename>, | |
| 74 | <filename>network.target</filename>, | |
| 75 | <filename>network-online.target</filename>, | |
| 76 | <filename>network-pre.target</filename>, | |
| 77 | <filename>nss-lookup.target</filename>, | |
| 78 | <filename>nss-user-lookup.target</filename>, | |
| 79 | <filename>paths.target</filename>, | |
| 80 | <filename>poweroff.target</filename>, | |
| 81 | <filename>printer.target</filename>, | |
| 82 | <filename>reboot.target</filename>, | |
| 83 | <filename>remote-fs.target</filename>, | |
| 84 | <filename>remote-fs-pre.target</filename>, | |
| 85 | <filename>rescue.target</filename>, | |
| 86 | <filename>initrd-root-fs.target</filename>, | |
| 87 | <filename>rpcbind.target</filename>, | |
| 88 | <filename>runlevel2.target</filename>, | |
| 89 | <filename>runlevel3.target</filename>, | |
| 90 | <filename>runlevel4.target</filename>, | |
| 91 | <filename>runlevel5.target</filename>, | |
| 92 | <filename>shutdown.target</filename>, | |
| 93 | <filename>sigpwr.target</filename>, | |
| 94 | <filename>sleep.target</filename>, | |
| 95 | <filename>smartcard.target</filename>, | |
| 96 | <filename>sockets.target</filename>, | |
| 97 | <filename>sound.target</filename>, | |
| 98 | <filename>suspend.target</filename>, | |
| 99 | <filename>swap.target</filename>, | |
| 100 | <filename>sysinit.target</filename>, | |
| 101 | <filename>syslog.socket</filename>, | |
| 102 | <filename>system-update.target</filename>, | |
| 103 | <filename>time-sync.target</filename>, | |
| 104 | <filename>timers.target</filename>, | |
| 105 | <filename>umount.target</filename>, | |
| 106 | <filename>-.slice</filename>, | |
| 107 | <filename>system.slice</filename>, | |
| 108 | <filename>user.slice</filename>, | |
| 109 | <filename>machine.slice</filename></para> | |
| 110 | </refsynopsisdiv> | |
| 111 | ||
| 112 | <refsect1> | |
| 113 | <title>Description</title> | |
| 114 | ||
| 115 | <para>A few units are treated specially by systemd. They have | |
| 116 | special internal semantics and cannot be renamed.</para> | |
| 117 | </refsect1> | |
| 118 | ||
| 119 | <refsect1> | |
| 120 | <title>Special System Units</title> | |
| 121 | ||
| 122 | <variablelist> | |
| 123 | <varlistentry> | |
| 124 | <term><filename>basic.target</filename></term> | |
| 125 | <listitem> | |
| 126 | <para>A special target unit covering basic boot-up.</para> | |
| 127 | ||
| 128 | <para>systemd automatically adds dependencies of the types | |
| 129 | <varname>Requires=</varname> and <varname>After=</varname> | |
| 130 | for this target unit to all services (except for those with | |
| 131 | <varname>DefaultDependencies=no</varname>).</para> | |
| 132 | ||
| b938cb90 | 133 | <para>Usually, this should pull-in all local mount points plus |
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134 | <filename>/var</filename>, <filename>/tmp</filename> and |
| 135 | <filename>/var/tmp</filename>, swap devices, sockets, timers, | |
| 136 | path units and other basic initialization necessary for general | |
| 137 | purpose daemons. The mentioned mount points are special cased | |
| 138 | to allow them to be remote. | |
| 139 | </para> | |
| 140 | ||
| 141 | <para>This target usually does not pull in any non-target units | |
| 142 | directly, but rather does so indirectly via other early boot targets. | |
| 143 | It is instead meant as a synchronization point for late boot | |
| 144 | services. Refer to | |
| 145 | <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
| 146 | for details on the targets involved. | |
| 147 | </para> | |
| 148 | ||
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149 | </listitem> |
| 150 | </varlistentry> | |
| 151 | <varlistentry> | |
| 152 | <term><filename>ctrl-alt-del.target</filename></term> | |
| 153 | <listitem> | |
| 154 | <para>systemd starts this target whenever Control+Alt+Del is | |
| b938cb90 | 155 | pressed on the console. Usually, this should be aliased |
| 798d3a52 ZJS |
156 | (symlinked) to <filename>reboot.target</filename>.</para> |
| 157 | </listitem> | |
| 158 | </varlistentry> | |
| 159 | <varlistentry> | |
| 160 | <term><filename>cryptsetup.target</filename></term> | |
| 161 | <listitem> | |
| 162 | <para>A target that pulls in setup services for all | |
| 163 | encrypted block devices.</para> | |
| 164 | </listitem> | |
| 165 | </varlistentry> | |
| 166 | <varlistentry> | |
| 167 | <term><filename>dbus.service</filename></term> | |
| 168 | <listitem> | |
| 169 | <para>A special unit for the D-Bus bus daemon. As soon as | |
| 170 | this service is fully started up systemd will connect to it | |
| 171 | and register its service.</para> | |
| 172 | </listitem> | |
| 173 | </varlistentry> | |
| 174 | <varlistentry> | |
| 175 | <term><filename>dbus.socket</filename></term> | |
| 176 | <listitem> | |
| 177 | <para>A special unit for the D-Bus system bus socket. All | |
| 178 | units with <varname>Type=dbus</varname> automatically gain a | |
| 179 | dependency on this unit.</para> | |
| 180 | </listitem> | |
| 181 | </varlistentry> | |
| 182 | <varlistentry> | |
| 183 | <term><filename>default.target</filename></term> | |
| 184 | <listitem> | |
| b938cb90 | 185 | <para>The default unit systemd starts at bootup. Usually, |
| 798d3a52 ZJS |
186 | this should be aliased (symlinked) to |
| 187 | <filename>multi-user.target</filename> or | |
| 188 | <filename>graphical.target</filename>.</para> | |
| 189 | ||
| 190 | <para>The default unit systemd starts at bootup can be | |
| 191 | overridden with the <varname>systemd.unit=</varname> kernel | |
| 192 | command line option.</para> | |
| 193 | </listitem> | |
| 194 | </varlistentry> | |
| 195 | <varlistentry> | |
| 196 | <term><filename>display-manager.service</filename></term> | |
| 197 | <listitem> | |
| b938cb90 | 198 | <para>The display manager service. Usually, this should be |
| 798d3a52 ZJS |
199 | aliased (symlinked) to <filename>gdm.service</filename> or a |
| 200 | similar display manager service.</para> | |
| 201 | </listitem> | |
| 202 | </varlistentry> | |
| 203 | <varlistentry> | |
| 204 | <term><filename>emergency.target</filename></term> | |
| 205 | <listitem> | |
| 206 | <para>A special target unit that starts an emergency shell | |
| 207 | on the main console. This unit is supposed to be used with | |
| 208 | the kernel command line option | |
| 209 | <varname>systemd.unit=</varname> and has otherwise little | |
| 210 | use. | |
| 211 | </para> | |
| 212 | </listitem> | |
| 213 | </varlistentry> | |
| 287419c1 AC |
214 | <varlistentry> |
| 215 | <term><filename>exit.target</filename></term> | |
| 216 | <listitem> | |
| 217 | <para>A special service unit for shutting down the system or | |
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218 | user service manager. It is equivalent to |
| 219 | <filename>poweroff.target</filename> on non-container | |
| 220 | systems, and also works in containers.</para> | |
| 287419c1 | 221 | |
| 9f4092e2 ZJS |
222 | <para>systemd will start this unit when it receives a |
| 223 | request to shut down over D-Bus or a | |
| 287419c1 | 224 | <constant>SIGTERM</constant> or <constant>SIGINT</constant> |
| 9f4092e2 | 225 | signal when running as user service daemon.</para> |
| 287419c1 | 226 | |
| 9f4092e2 | 227 | <para>Normally, this (indirectly) pulls in |
| b938cb90 | 228 | <filename>shutdown.target</filename>, which in turn should be |
| 9f4092e2 ZJS |
229 | conflicted by all units that want to be scheduled for |
| 230 | shutdown when the service manager starts to exit.</para> | |
| 287419c1 AC |
231 | </listitem> |
| 232 | </varlistentry> | |
| 798d3a52 ZJS |
233 | <varlistentry> |
| 234 | <term><filename>final.target</filename></term> | |
| 235 | <listitem> | |
| 236 | <para>A special target unit that is used during the shutdown | |
| 237 | logic and may be used to pull in late services after all | |
| 238 | normal services are already terminated and all mounts | |
| 239 | unmounted. | |
| 240 | </para> | |
| 241 | </listitem> | |
| 242 | </varlistentry> | |
| 243 | <varlistentry> | |
| 244 | <term><filename>getty.target</filename></term> | |
| 245 | <listitem> | |
| 246 | <para>A special target unit that pulls in statically | |
| 247 | configured local TTY <filename>getty</filename> instances. | |
| 248 | </para> | |
| 249 | </listitem> | |
| 250 | </varlistentry> | |
| 251 | <varlistentry> | |
| 252 | <term><filename>graphical.target</filename></term> | |
| 253 | <listitem> | |
| 254 | <para>A special target unit for setting up a graphical login | |
| 255 | screen. This pulls in | |
| 256 | <filename>multi-user.target</filename>.</para> | |
| 257 | ||
| 258 | <para>Units that are needed for graphical logins shall add | |
| 259 | <varname>Wants=</varname> dependencies for their unit to | |
| 260 | this unit (or <filename>multi-user.target</filename>) during | |
| 261 | installation. This is best configured via | |
| 262 | <varname>WantedBy=graphical.target</varname> in the unit's | |
| 263 | <literal>[Install]</literal> section.</para> | |
| 264 | </listitem> | |
| 265 | </varlistentry> | |
| 266 | <varlistentry> | |
| 267 | <term><filename>hibernate.target</filename></term> | |
| 268 | <listitem> | |
| 269 | <para>A special target unit for hibernating the system. This | |
| 270 | pulls in <filename>sleep.target</filename>.</para> | |
| 271 | </listitem> | |
| 272 | </varlistentry> | |
| 273 | <varlistentry> | |
| 274 | <term><filename>hybrid-sleep.target</filename></term> | |
| 275 | <listitem> | |
| 276 | <para>A special target unit for hibernating and suspending | |
| 277 | the system at the same time. This pulls in | |
| 278 | <filename>sleep.target</filename>.</para> | |
| 279 | </listitem> | |
| 280 | </varlistentry> | |
| 281 | <varlistentry> | |
| 282 | <term><filename>halt.target</filename></term> | |
| 283 | <listitem> | |
| 284 | <para>A special target unit for shutting down and halting | |
| 285 | the system. Note that this target is distinct from | |
| 286 | <filename>poweroff.target</filename> in that it generally | |
| 287 | really just halts the system rather than powering it | |
| 288 | down.</para> | |
| 289 | ||
| 290 | <para>Applications wanting to halt the system should start | |
| 291 | this unit.</para> | |
| 292 | </listitem> | |
| 293 | </varlistentry> | |
| 294 | <varlistentry> | |
| 295 | <term><filename>initrd-fs.target</filename></term> | |
| 296 | <listitem> | |
| 297 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 298 | automatically adds dependencies of type | |
| 299 | <varname>Before=</varname> to | |
| 300 | <filename>sysroot-usr.mount</filename> and all mount points | |
| 301 | found in <filename>/etc/fstab</filename> that have | |
| 302 | <option>x-initrd.mount</option> and not have | |
| 303 | <option>noauto</option> mount options set.</para> | |
| 304 | </listitem> | |
| 305 | </varlistentry> | |
| 306 | <varlistentry> | |
| 307 | <term><filename>kbrequest.target</filename></term> | |
| 308 | <listitem> | |
| 309 | <para>systemd starts this target whenever Alt+ArrowUp is | |
| 310 | pressed on the console. This is a good candidate to be | |
| 311 | aliased (symlinked) to | |
| 312 | <filename>rescue.target</filename>.</para> | |
| 313 | </listitem> | |
| 314 | </varlistentry> | |
| 315 | <varlistentry> | |
| 316 | <term><filename>kexec.target</filename></term> | |
| 317 | <listitem> | |
| 318 | <para>A special target unit for shutting down and rebooting | |
| 319 | the system via kexec.</para> | |
| 320 | ||
| 321 | <para>Applications wanting to reboot the system with kexec | |
| 322 | should start this unit.</para> | |
| 323 | </listitem> | |
| 324 | </varlistentry> | |
| 325 | <varlistentry> | |
| 326 | <term><filename>local-fs.target</filename></term> | |
| 327 | <listitem> | |
| 328 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 329 | automatically adds dependencies of type | |
| 330 | <varname>Before=</varname> to all mount units that refer to | |
| 331 | local mount points for this target unit. In addition, it | |
| 332 | adds dependencies of type <varname>Wants=</varname> to this | |
| 333 | target unit for those mounts listed in | |
| 334 | <filename>/etc/fstab</filename> that have the | |
| 335 | <option>auto</option> mount option set.</para> | |
| 336 | </listitem> | |
| 337 | </varlistentry> | |
| 338 | <varlistentry> | |
| 339 | <term><filename>multi-user.target</filename></term> | |
| 340 | <listitem> | |
| 341 | <para>A special target unit for setting up a multi-user | |
| 342 | system (non-graphical). This is pulled in by | |
| 343 | <filename>graphical.target</filename>.</para> | |
| 344 | ||
| 345 | <para>Units that are needed for a multi-user system shall | |
| 346 | add <varname>Wants=</varname> dependencies for their unit to | |
| 347 | this unit during installation. This is best configured via | |
| 348 | <varname>WantedBy=multi-user.target</varname> in the unit's | |
| 349 | <literal>[Install]</literal> section.</para> | |
| 350 | </listitem> | |
| 351 | </varlistentry> | |
| 352 | <varlistentry> | |
| 353 | <term><filename>network-online.target</filename></term> | |
| 354 | <listitem> | |
| 355 | <para>Units that strictly require a configured network | |
| 356 | connection should pull in | |
| 357 | <filename>network-online.target</filename> (via a | |
| 358 | <varname>Wants=</varname> type dependency) and order | |
| 359 | themselves after it. This target unit is intended to pull in | |
| 360 | a service that delays further execution until the network is | |
| 361 | sufficiently set up. What precisely this requires is left to | |
| 362 | the implementation of the network managing service.</para> | |
| 363 | ||
| 364 | <para>Note the distinction between this unit and | |
| 365 | <filename>network.target</filename>. This unit is an active | |
| 366 | unit (i.e. pulled in by the consumer rather than the | |
| 367 | provider of this functionality) and pulls in a service which | |
| 368 | possibly adds substantial delays to further execution. In | |
| 369 | contrast, <filename>network.target</filename> is a passive | |
| 370 | unit (i.e. pulled in by the provider of the functionality, | |
| 371 | rather than the consumer) that usually does not delay | |
| 372 | execution much. Usually, <filename>network.target</filename> | |
| 373 | is part of the boot of most systems, while | |
| 374 | <filename>network-online.target</filename> is not, except | |
| 375 | when at least one unit requires it. Also see <ulink | |
| 376 | url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running | |
| 377 | Services After the Network is up</ulink> for more | |
| 378 | information.</para> | |
| 379 | ||
| 380 | <para>All mount units for remote network file systems | |
| 381 | automatically pull in this unit, and order themselves after | |
| 382 | it. Note that networking daemons that simply provide | |
| 383 | functionality to other hosts generally do not need to pull | |
| 384 | this in.</para> | |
| 385 | </listitem> | |
| 386 | </varlistentry> | |
| 387 | <varlistentry> | |
| 388 | <term><filename>paths.target</filename></term> | |
| 389 | <listitem> | |
| 390 | <para>A special target unit that sets up all path units (see | |
| 391 | <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
| 392 | for details) that shall be active after boot.</para> | |
| 393 | ||
| 394 | <para>It is recommended that path units installed by | |
| 395 | applications get pulled in via <varname>Wants=</varname> | |
| 396 | dependencies from this unit. This is best configured via a | |
| 397 | <varname>WantedBy=paths.target</varname> in the path unit's | |
| 398 | <literal>[Install]</literal> section.</para> | |
| 399 | </listitem> | |
| 400 | </varlistentry> | |
| 401 | <varlistentry> | |
| 402 | <term><filename>poweroff.target</filename></term> | |
| 403 | <listitem> | |
| 404 | <para>A special target unit for shutting down and powering | |
| 405 | off the system.</para> | |
| 406 | ||
| 407 | <para>Applications wanting to power off the system should | |
| 408 | start this unit.</para> | |
| 409 | ||
| 410 | <para><filename>runlevel0.target</filename> is an alias for | |
| 411 | this target unit, for compatibility with SysV.</para> | |
| 412 | </listitem> | |
| 413 | </varlistentry> | |
| 414 | <varlistentry> | |
| 415 | <term><filename>reboot.target</filename></term> | |
| 416 | <listitem> | |
| 417 | <para>A special target unit for shutting down and rebooting | |
| 418 | the system.</para> | |
| 419 | ||
| 420 | <para>Applications wanting to reboot the system should start | |
| 421 | this unit.</para> | |
| 422 | ||
| 423 | <para><filename>runlevel6.target</filename> is an alias for | |
| 424 | this target unit, for compatibility with SysV.</para> | |
| 425 | </listitem> | |
| 426 | </varlistentry> | |
| 427 | <varlistentry> | |
| 428 | <term><filename>remote-fs.target</filename></term> | |
| 429 | <listitem> | |
| 430 | <para>Similar to <filename>local-fs.target</filename>, but | |
| 431 | for remote mount points.</para> | |
| 432 | ||
| 433 | <para>systemd automatically adds dependencies of type | |
| 434 | <varname>After=</varname> for this target unit to all SysV | |
| 435 | init script service units with an LSB header referring to | |
| 436 | the <literal>$remote_fs</literal> facility.</para> | |
| 437 | </listitem> | |
| 438 | </varlistentry> | |
| 439 | <varlistentry> | |
| 440 | <term><filename>rescue.target</filename></term> | |
| 441 | <listitem> | |
| 442 | <para>A special target unit for setting up the base system | |
| 443 | and a rescue shell.</para> | |
| 444 | ||
| 445 | <para><filename>runlevel1.target</filename> is an alias for | |
| 446 | this target unit, for compatibility with SysV.</para> | |
| 447 | </listitem> | |
| 448 | </varlistentry> | |
| 449 | <varlistentry> | |
| 450 | <term><filename>initrd-root-fs.target</filename></term> | |
| 451 | <listitem> | |
| 452 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 453 | automatically adds dependencies of type | |
| 454 | <varname>Before=</varname> to the | |
| 455 | <filename>sysroot.mount</filename> unit, which is generated | |
| 456 | from the kernel command line. | |
| 457 | </para> | |
| 458 | </listitem> | |
| 459 | </varlistentry> | |
| 460 | <varlistentry> | |
| 461 | <term><filename>runlevel2.target</filename></term> | |
| 462 | <term><filename>runlevel3.target</filename></term> | |
| 463 | <term><filename>runlevel4.target</filename></term> | |
| 464 | <term><filename>runlevel5.target</filename></term> | |
| 465 | <listitem> | |
| 466 | <para>These are targets that are called whenever the SysV | |
| 467 | compatibility code asks for runlevel 2, 3, 4, 5, | |
| 468 | respectively. It is a good idea to make this an alias for | |
| 469 | (i.e. symlink to) <filename>multi-user.target</filename> | |
| 470 | (for runlevel 2) or <filename>graphical.target</filename> | |
| 471 | (the others).</para> | |
| 472 | </listitem> | |
| 473 | </varlistentry> | |
| 474 | <varlistentry> | |
| 475 | <term><filename>shutdown.target</filename></term> | |
| 476 | <listitem> | |
| 477 | <para>A special target unit that terminates the services on | |
| 478 | system shutdown.</para> | |
| 479 | ||
| 480 | <para>Services that shall be terminated on system shutdown | |
| 481 | shall add <varname>Conflicts=</varname> dependencies to this | |
| 482 | unit for their service unit, which is implicitly done when | |
| 483 | <varname>DefaultDependencies=yes</varname> is set (the | |
| 484 | default).</para> | |
| 485 | </listitem> | |
| 486 | </varlistentry> | |
| 487 | <varlistentry> | |
| 488 | <term><filename>sigpwr.target</filename></term> | |
| 489 | <listitem> | |
| 490 | <para>A special target that is started when systemd receives | |
| 491 | the SIGPWR process signal, which is normally sent by the | |
| 492 | kernel or UPS daemons when power fails.</para> | |
| 493 | </listitem> | |
| 494 | </varlistentry> | |
| 495 | <varlistentry> | |
| 496 | <term><filename>sleep.target</filename></term> | |
| 497 | <listitem> | |
| 498 | <para>A special target unit that is pulled in by | |
| 499 | <filename>suspend.target</filename>, | |
| 500 | <filename>hibernate.target</filename> and | |
| 501 | <filename>hybrid-sleep.target</filename> and may be used to | |
| 502 | hook units into the sleep state logic.</para> | |
| 503 | </listitem> | |
| 504 | </varlistentry> | |
| 505 | <varlistentry> | |
| 506 | <term><filename>sockets.target</filename></term> | |
| 507 | <listitem> | |
| 508 | <para>A special target unit that sets up all socket | |
| 509 | units.(see | |
| 510 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
| 511 | for details) that shall be active after boot.</para> | |
| 512 | ||
| 513 | <para>Services that can be socket-activated shall add | |
| 514 | <varname>Wants=</varname> dependencies to this unit for | |
| 515 | their socket unit during installation. This is best | |
| 516 | configured via a <varname>WantedBy=sockets.target</varname> | |
| 517 | in the socket unit's <literal>[Install]</literal> | |
| 518 | section.</para> | |
| 519 | </listitem> | |
| 520 | </varlistentry> | |
| 521 | <varlistentry> | |
| 522 | <term><filename>suspend.target</filename></term> | |
| 523 | <listitem> | |
| 524 | <para>A special target unit for suspending the system. This | |
| 525 | pulls in <filename>sleep.target</filename>.</para> | |
| 526 | </listitem> | |
| 527 | </varlistentry> | |
| 528 | <varlistentry> | |
| 529 | <term><filename>swap.target</filename></term> | |
| 530 | <listitem> | |
| 531 | <para>Similar to <filename>local-fs.target</filename>, but | |
| 532 | for swap partitions and swap files.</para> | |
| 533 | </listitem> | |
| 534 | </varlistentry> | |
| 535 | <varlistentry> | |
| 536 | <term><filename>sysinit.target</filename></term> | |
| 537 | <listitem> | |
| 913a9869 FS |
538 | <para>This target pulls in the services required for system |
| 539 | initialization. System services pulled in by this target should | |
| 540 | declare <varname>DefaultDependencies=no</varname> and specify | |
| 541 | all their dependencies manually, including access to anything | |
| 542 | more than a read only root filesystem. For details on the | |
| 543 | dependencies of this target, refer to | |
| 544 | <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>. | |
| 545 | </para> | |
| 798d3a52 ZJS |
546 | </listitem> |
| 547 | </varlistentry> | |
| 548 | <varlistentry> | |
| 549 | <term><filename>syslog.socket</filename></term> | |
| 550 | <listitem> | |
| 551 | <para>The socket unit syslog implementations should listen | |
| 552 | on. All userspace log messages will be made available on | |
| 553 | this socket. For more information about syslog integration, | |
| 554 | please consult the <ulink | |
| 555 | url="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog | |
| 556 | Interface</ulink> document.</para> | |
| 557 | </listitem> | |
| 558 | </varlistentry> | |
| 559 | <varlistentry> | |
| 560 | <term><filename>system-update.target</filename></term> | |
| 561 | <listitem> | |
| 562 | <para>A special target unit that is used for off-line system | |
| 563 | updates. | |
| 564 | <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
| 565 | will redirect the boot process to this target if | |
| 566 | <filename>/system-update</filename> exists. For more | |
| 567 | information see the <ulink | |
| 568 | url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System | |
| 569 | Updates Specification</ulink>.</para> | |
| 570 | </listitem> | |
| 571 | </varlistentry> | |
| 572 | <varlistentry> | |
| 573 | <term><filename>timers.target</filename></term> | |
| 574 | <listitem> | |
| 575 | <para>A special target unit that sets up all timer units | |
| 576 | (see | |
| 577 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
| 578 | for details) that shall be active after boot.</para> | |
| 579 | ||
| 580 | <para>It is recommended that timer units installed by | |
| 581 | applications get pulled in via <varname>Wants=</varname> | |
| 582 | dependencies from this unit. This is best configured via | |
| 583 | <varname>WantedBy=timers.target</varname> in the timer | |
| 584 | unit's <literal>[Install]</literal> section.</para> | |
| 585 | </listitem> | |
| 586 | </varlistentry> | |
| 587 | <varlistentry> | |
| 588 | <term><filename>umount.target</filename></term> | |
| 589 | <listitem> | |
| 590 | <para>A special target unit that umounts all mount and | |
| 591 | automount points on system shutdown.</para> | |
| 592 | ||
| 593 | <para>Mounts that shall be unmounted on system shutdown | |
| 594 | shall add Conflicts dependencies to this unit for their | |
| 595 | mount unit, which is implicitly done when | |
| 596 | <varname>DefaultDependencies=yes</varname> is set (the | |
| 597 | default).</para> | |
| 598 | </listitem> | |
| 599 | </varlistentry> | |
| 600 | ||
| 601 | </variablelist> | |
| 602 | </refsect1> | |
| 603 | ||
| 604 | <refsect1> | |
| 605 | <title>Special System Units for Devices</title> | |
| 606 | ||
| 607 | <para>Some target units are automatically pulled in as devices of | |
| 608 | certain kinds show up in the system. These may be used to | |
| 609 | automatically activate various services based on the specific type | |
| 610 | of the available hardware.</para> | |
| 611 | ||
| 612 | <variablelist> | |
| 613 | <varlistentry> | |
| 614 | <term><filename>bluetooth.target</filename></term> | |
| 615 | <listitem> | |
| 616 | <para>This target is started automatically as soon as a | |
| 617 | Bluetooth controller is plugged in or becomes available at | |
| 618 | boot.</para> | |
| 619 | ||
| 620 | <para>This may be used to pull in Bluetooth management | |
| 621 | daemons dynamically when Bluetooth hardware is found.</para> | |
| 622 | </listitem> | |
| 623 | </varlistentry> | |
| 624 | <varlistentry> | |
| 625 | <term><filename>printer.target</filename></term> | |
| 626 | <listitem> | |
| 627 | <para>This target is started automatically as soon as a | |
| 628 | printer is plugged in or becomes available at boot.</para> | |
| 629 | ||
| 630 | <para>This may be used to pull in printer management daemons | |
| 631 | dynamically when printer hardware is found.</para> | |
| 632 | </listitem> | |
| 633 | </varlistentry> | |
| 634 | <varlistentry> | |
| 635 | <term><filename>smartcard.target</filename></term> | |
| 636 | <listitem> | |
| 637 | <para>This target is started automatically as soon as a | |
| 638 | smartcard controller is plugged in or becomes available at | |
| 639 | boot.</para> | |
| 640 | ||
| 641 | <para>This may be used to pull in smartcard management | |
| 642 | daemons dynamically when smartcard hardware is found.</para> | |
| 643 | </listitem> | |
| 644 | </varlistentry> | |
| 645 | <varlistentry> | |
| 646 | <term><filename>sound.target</filename></term> | |
| 647 | <listitem> | |
| 648 | <para>This target is started automatically as soon as a | |
| 649 | sound card is plugged in or becomes available at | |
| 650 | boot.</para> | |
| 651 | ||
| 652 | <para>This may be used to pull in audio management daemons | |
| 653 | dynamically when audio hardware is found.</para> | |
| 654 | </listitem> | |
| 655 | </varlistentry> | |
| 656 | </variablelist> | |
| 657 | </refsect1> | |
| 658 | ||
| 659 | <refsect1> | |
| 660 | <title>Special Passive System Units </title> | |
| 661 | ||
| 662 | <para>A number of special system targets are defined that can be | |
| 663 | used to properly order boot-up of optional services. These targets | |
| 664 | are generally not part of the initial boot transaction, unless | |
| 665 | they are explicitly pulled in by one of the implementing services. | |
| 666 | Note specifically that these <emphasis>passive</emphasis> target | |
| 667 | units are generally not pulled in by the consumer of a service, | |
| 668 | but by the provider of the service. This means: a consuming | |
| 669 | service should order itself after these targets (as appropriate), | |
| 670 | but not pull it in. A providing service should order itself before | |
| 671 | these targets (as appropriate) and pull it in (via a | |
| 672 | <varname>Wants=</varname> type dependency).</para> | |
| 673 | ||
| 674 | <para>Note that these passive units cannot be started manually, | |
| 675 | i.e. <literal>systemctl start time-sync.target</literal> will fail | |
| 676 | with an error. They can only be pulled in by dependency. This is | |
| 677 | enforced since they exist for ordering purposes only and thus are | |
| 678 | not useful as only unit within a transaction.</para> | |
| 679 | ||
| 680 | <variablelist> | |
| 681 | <varlistentry> | |
| 682 | <term><filename>cryptsetup-pre.target</filename></term> | |
| 683 | <listitem> | |
| 684 | <para>This passive target unit may be pulled in by services | |
| 685 | that want to run before any encrypted block device is set | |
| 686 | up. All encrypted block devices are set up after this target | |
| 687 | has been reached. Since the shutdown order is implicitly the | |
| 688 | reverse start-up order between units, this target is | |
| 689 | particularly useful to ensure that a service is shut down | |
| 690 | only after all encrypted block devices are fully | |
| 691 | stopped.</para> | |
| 692 | </listitem> | |
| 693 | </varlistentry> | |
| 694 | <varlistentry> | |
| 695 | <term><filename>local-fs-pre.target</filename></term> | |
| 696 | <listitem> | |
| 697 | <para>This target unit is | |
| 698 | automatically ordered before | |
| 699 | all local mount points marked | |
| 700 | with <option>auto</option> | |
| 701 | (see above). It can be used to | |
| 702 | execute certain units before | |
| 703 | all local mounts.</para> | |
| 704 | </listitem> | |
| 705 | </varlistentry> | |
| 706 | <varlistentry> | |
| 707 | <term><filename>network.target</filename></term> | |
| 708 | <listitem> | |
| 709 | <para>This unit is supposed to indicate when network | |
| 710 | functionality is available, but it is only very weakly | |
| 711 | defined what that is supposed to mean, with one exception: | |
| 712 | at shutdown, a unit that is ordered after | |
| 713 | <filename>network.target</filename> will be stopped before | |
| 714 | the network -- to whatever level it might be set up then -- | |
| 715 | is shut down. It is hence useful when writing service files | |
| 716 | that require network access on shutdown, which should order | |
| 717 | themselves after this target, but not pull it in. Also see | |
| 718 | <ulink url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running | |
| 719 | Services After the Network is up</ulink> for more | |
| 720 | information. Also see | |
| 721 | <filename>network-online.target</filename> described | |
| 722 | above.</para> | |
| 723 | ||
| 724 | <para>systemd automatically adds dependencies of type | |
| 725 | <varname>After=</varname> for this target unit to all SysV | |
| 726 | init script service units with an LSB header referring to | |
| 727 | the <literal>$network</literal> facility.</para> | |
| 728 | </listitem> | |
| 729 | </varlistentry> | |
| 730 | <varlistentry> | |
| 731 | <term><filename>network-pre.target</filename></term> | |
| 732 | <listitem> | |
| 733 | <para>This passive target unit may be pulled in by services | |
| 734 | that want to run before any network is set up, for example | |
| 735 | for the purpose of setting up a firewall. All network | |
| 736 | management software orders itself after this target, but | |
| 737 | does not pull it in.</para> | |
| 738 | </listitem> | |
| 739 | </varlistentry> | |
| 740 | <varlistentry> | |
| 741 | <term><filename>nss-lookup.target</filename></term> | |
| 742 | <listitem> | |
| 743 | <para>A target that should be used as synchronization point | |
| 744 | for all host/network name service lookups. Note that this is | |
| 745 | independent of user/group name lookups for which | |
| 746 | <filename>nss-user-lookup.target</filename> should be used. | |
| 747 | All services for which the availability of full host/network | |
| 748 | name resolution is essential should be ordered after this | |
| 749 | target, but not pull it in. systemd automatically adds | |
| 750 | dependencies of type <varname>After=</varname> for this | |
| 751 | target unit to all SysV init script service units with an | |
| 752 | LSB header referring to the <literal>$named</literal> | |
| 753 | facility.</para> | |
| 754 | </listitem> | |
| 755 | </varlistentry> | |
| 756 | <varlistentry> | |
| 757 | <term><filename>nss-user-lookup.target</filename></term> | |
| 758 | <listitem> | |
| 759 | <para>A target that should be used as synchronization point | |
| 760 | for all user/group name service lookups. Note that this is | |
| 761 | independent of host/network name lookups for which | |
| 762 | <filename>nss-lookup.target</filename> should be used. All | |
| 763 | services for which the availability of the full user/group | |
| 764 | database is essential should be ordered after this target, | |
| 765 | but not pull it in. Note that system users are always | |
| 766 | resolvable, and hence do not require any special ordering | |
| 767 | against this target.</para> | |
| 768 | </listitem> | |
| 769 | </varlistentry> | |
| 770 | <varlistentry> | |
| 771 | <term><filename>remote-fs-pre.target</filename></term> | |
| 772 | <listitem> | |
| 773 | <para>This target unit is automatically ordered before all | |
| 774 | remote mount point units (see above). It can be used to run | |
| 775 | certain units before the remote mounts are established. Note | |
| 776 | that this unit is generally not part of the initial | |
| 777 | transaction, unless the unit that wants to be ordered before | |
| 778 | all remote mounts pulls it in via a | |
| 779 | <varname>Wants=</varname> type dependency. If the unit wants | |
| 780 | to be pulled in by the first remote mount showing up, it | |
| 781 | should use <filename>network-online.target</filename> (see | |
| 782 | above).</para> | |
| 783 | </listitem> | |
| 784 | </varlistentry> | |
| 785 | <varlistentry> | |
| 786 | <term><filename>rpcbind.target</filename></term> | |
| 787 | <listitem> | |
| 788 | <para>The portmapper/rpcbind pulls in this target and orders | |
| 789 | itself before it, to indicate its availability. systemd | |
| 790 | automatically adds dependencies of type | |
| 791 | <varname>After=</varname> for this target unit to all SysV | |
| 792 | init script service units with an LSB header referring to | |
| 793 | the <literal>$portmap</literal> facility.</para> | |
| 794 | </listitem> | |
| 795 | </varlistentry> | |
| 796 | <varlistentry> | |
| 797 | <term><filename>time-sync.target</filename></term> | |
| 798 | <listitem> | |
| 799 | <para>Services responsible for synchronizing the system | |
| 800 | clock from a remote source (such as NTP client | |
| 801 | implementations) should pull in this target and order | |
| 802 | themselves before it. All services where correct time is | |
| 803 | essential should be ordered after this unit, but not pull it | |
| 804 | in. systemd automatically adds dependencies of type | |
| 805 | <varname>After=</varname> for this target unit to all SysV | |
| 806 | init script service units with an LSB header referring to | |
| 807 | the <literal>$time</literal> facility. </para> | |
| 808 | </listitem> | |
| 809 | </varlistentry> | |
| 810 | </variablelist> | |
| 811 | </refsect1> | |
| 812 | ||
| 813 | <refsect1> | |
| 814 | <title>Special User Units</title> | |
| 815 | ||
| 816 | <para>When systemd runs as a user instance, the following special | |
| 817 | units are available, which have similar definitions as their | |
| 818 | system counterparts: | |
| 287419c1 | 819 | <filename>exit.target</filename>, |
| 798d3a52 ZJS |
820 | <filename>default.target</filename>, |
| 821 | <filename>shutdown.target</filename>, | |
| 822 | <filename>sockets.target</filename>, | |
| 823 | <filename>timers.target</filename>, | |
| 824 | <filename>paths.target</filename>, | |
| 825 | <filename>bluetooth.target</filename>, | |
| 826 | <filename>printer.target</filename>, | |
| 827 | <filename>smartcard.target</filename>, | |
| 828 | <filename>sound.target</filename>.</para> | |
| 798d3a52 ZJS |
829 | </refsect1> |
| 830 | ||
| 831 | <refsect1> | |
| 832 | <title>Special Slice Units</title> | |
| 833 | ||
| 834 | <para>There are four <literal>.slice</literal> units which form | |
| 835 | the basis of the hierarchy for assignment of resources for | |
| 836 | services, users, and virtual machines or containers.</para> | |
| 837 | ||
| 838 | <variablelist> | |
| 839 | <varlistentry> | |
| 840 | <term><filename>-.slice</filename></term> | |
| 841 | <listitem> | |
| 842 | <para>The root slice is the root of the hierarchy. It | |
| 843 | usually does not contain units directly, but may be used to | |
| 844 | set defaults for the whole tree.</para> | |
| 845 | </listitem> | |
| 846 | </varlistentry> | |
| 847 | ||
| 848 | <varlistentry> | |
| 849 | <term><filename>system.slice</filename></term> | |
| 850 | <listitem> | |
| 694223fb | 851 | <para>By default, all system services started by |
| 798d3a52 ZJS |
852 | <command>systemd</command> are found in this slice.</para> |
| 853 | </listitem> | |
| 854 | </varlistentry> | |
| 855 | ||
| 856 | <varlistentry> | |
| 857 | <term><filename>user.slice</filename></term> | |
| 858 | <listitem> | |
| 859 | <para>By default, all user processes and services started on | |
| 860 | behalf of the user, including the per-user systemd instance | |
| 861 | are found in this slice.</para> | |
| 862 | </listitem> | |
| 863 | </varlistentry> | |
| 864 | ||
| 865 | <varlistentry> | |
| 866 | <term><filename>machine.slice</filename></term> | |
| 867 | <listitem> | |
| 868 | <para>By default, all virtual machines and containers | |
| 869 | registered with <command>systemd-machined</command> are | |
| 870 | found in this slice. | |
| 871 | </para> | |
| 872 | </listitem> | |
| 873 | </varlistentry> | |
| 874 | </variablelist> | |
| 875 | </refsect1> | |
| 876 | ||
| 877 | <refsect1> | |
| 878 | <title>See Also</title> | |
| 879 | <para> | |
| 880 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
| 881 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 882 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 883 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 884 | <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 885 | <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 886 | <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
| 887 | <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
| 888 | </para> | |
| 889 | </refsect1> | |
| 9f235308 LP |
890 | |
| 891 | </refentry> |