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" | |
| 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
| 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 | |
| 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 | ||
| 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 | |
| 18 | General Public License for more details. | |
| 19 | ||
| 20 | You should have received a copy of the GNU General Public License | |
| 21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
| 22 | --> | |
| 23 | ||
| 24 | <refentry id="systemd"> | |
| 25 | ||
| 26 | <refentryinfo> | |
| 27 | <title>systemd</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</refentrytitle> | |
| 160cd5c9 | 42 | <manvolnum>1</manvolnum> |
| 9e632bf7 LP |
43 | </refmeta> |
| 44 | ||
| 45 | <refnamediv> | |
| 46 | <refname>systemd</refname> | |
| 6f6083dc | 47 | <refname>init</refname> |
| 9e632bf7 LP |
48 | <refpurpose>systemd System and Session Manager</refpurpose> |
| 49 | </refnamediv> | |
| 50 | ||
| 2218198b LP |
51 | <refsynopsisdiv> |
| 52 | <cmdsynopsis> | |
| 160cd5c9 | 53 | <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command> |
| 2218198b LP |
54 | </cmdsynopsis> |
| 55 | <cmdsynopsis> | |
| 160cd5c9 | 56 | <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command> |
| 2218198b LP |
57 | </cmdsynopsis> |
| 58 | </refsynopsisdiv> | |
| 59 | ||
| 9e632bf7 LP |
60 | <refsect1> |
| 61 | <title>Description</title> | |
| 62 | ||
| 2218198b LP |
63 | <para>systemd is a system and session manager for |
| 64 | Linux operating systems. When run as first process on | |
| af62c704 KS |
65 | boot (as PID 1), it acts as init system that brings |
| 66 | up and maintains userspace services.</para> | |
| 2218198b | 67 | |
| af62c704 | 68 | <para>For compatibility with SysV, if systemd is called |
| 2218198b | 69 | as <command>init</command> and a PID that is not |
| af62c704 | 70 | 1, it will execute <command>telinit</command> and pass |
| 2218198b LP |
71 | all command line arguments unmodified. That means |
| 72 | <command>init</command> and <command>telinit</command> | |
| 73 | are mostly equivalent when invoked from normal login sessions. See | |
| 74 | <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
| 75 | for more information.</para> | |
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76 | |
| 77 | <para>When run as system instance, systemd interprets | |
| 78 | the configuration file | |
| 79 | <filename>system.conf</filename>, otherwise | |
| 80 | <filename>session.conf</filename>. See | |
| 81 | <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
| 82 | for more information.</para> | |
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83 | </refsect1> |
| 84 | ||
| 85 | <refsect1> | |
| 86 | <title>Options</title> | |
| 87 | ||
| 88 | <para>The following options are understood:</para> | |
| 89 | ||
| 90 | <variablelist> | |
| 91 | <varlistentry> | |
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92 | <term><option>-h</option></term> |
| 93 | <term><option>--help</option></term> | |
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94 | |
| 95 | <listitem><para>Prints a short help | |
| 96 | text and exits.</para></listitem> | |
| 97 | </varlistentry> | |
| f3e219a2 LP |
98 | <varlistentry> |
| 99 | <term><option>--test</option></term> | |
| 100 | ||
| 101 | <listitem><para>Determine startup | |
| 102 | sequence, dump it and exit. This is an | |
| 103 | option useful for debugging | |
| 104 | only.</para></listitem> | |
| 105 | </varlistentry> | |
| 106 | <varlistentry> | |
| 107 | <term><option>--dump-configuration-items</option></term> | |
| 108 | ||
| 109 | <listitem><para>Dump understood unit | |
| 110 | configuration items. This outputs a | |
| 111 | terse but complete list of | |
| 112 | configuration items understood in unit | |
| 113 | definition files.</para></listitem> | |
| 114 | </varlistentry> | |
| 115 | <varlistentry> | |
| 116 | <term><option>--introspect=</option></term> | |
| 117 | ||
| 118 | <listitem><para>Extract D-Bus | |
| 119 | interface introspection data. This is | |
| ad678a06 | 120 | mostly useful at install time |
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121 | to generate data suitable for the |
| 122 | D-Bus interfaces | |
| 123 | repository. Optionally the interface | |
| 124 | name for the introspection data may be | |
| 125 | specified. If omitted, the | |
| 126 | introspection data for all interfaces | |
| 127 | is dumped.</para></listitem> | |
| 128 | </varlistentry> | |
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129 | <varlistentry> |
| 130 | <term><option>--unit=</option></term> | |
| 131 | ||
| 132 | <listitem><para>Set default unit to | |
| 133 | activate on startup. If not specified | |
| 134 | defaults to | |
| 135 | <filename>default.target</filename>.</para></listitem> | |
| 136 | </varlistentry> | |
| 137 | <varlistentry> | |
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138 | <term><option>--system</option></term> |
| 139 | <term><option>--session</option></term> | |
| 140 | ||
| 141 | <listitem><para>Tell systemd to run a | |
| 142 | system instance (resp. session | |
| 143 | instance), even if the process ID is | |
| 144 | not 1 (resp. is 1), i.e. system is not | |
| 145 | (resp. is) run as init process. | |
| 146 | Normally it should not be necessary to | |
| 147 | pass these options, as systemd | |
| 148 | automatically detects the mode it is | |
| 149 | started in. These options are hence of | |
| 150 | little use except for | |
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151 | debugging.</para></listitem> |
| 152 | </varlistentry> | |
| 153 | <varlistentry> | |
| f3e219a2 | 154 | <term><option>--dump-core</option></term> |
| 2218198b | 155 | |
| f3e219a2 | 156 | <listitem><para>Dump core on crash. This switch has no effect when run as session instance.</para></listitem> |
| 2218198b LP |
157 | </varlistentry> |
| 158 | <varlistentry> | |
| f3e219a2 | 159 | <term><option>--crash-shell</option></term> |
| 2218198b | 160 | |
| f3e219a2 | 161 | <listitem><para>Run shell on crash. This switch has no effect when run as session instance.</para></listitem> |
| 2218198b LP |
162 | </varlistentry> |
| 163 | <varlistentry> | |
| 164 | <term><option>--confirm-spawn</option></term> | |
| 165 | ||
| f3e219a2 | 166 | <listitem><para>Ask for confirmation when spawning processes. This switch has no effect when run as session instance.</para></listitem> |
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167 | </varlistentry> |
| 168 | <varlistentry> | |
| f3e219a2 | 169 | <term><option>--show-status</option></term> |
| 2218198b | 170 | |
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171 | <listitem><para>Show terse service status information while booting. This switch has no effect when run as session instance.</para></listitem> |
| 172 | </varlistentry> | |
| 173 | <varlistentry> | |
| 174 | <term><option>--log-target=</option></term> | |
| 175 | ||
| 176 | <listitem><para>Set log | |
| 177 | target. Argument must be one of | |
| 178 | <option>console</option>, | |
| 179 | <option>syslog</option>, | |
| 180 | <option>kmsg</option>, | |
| 181 | <option>syslog-or-kmsg</option>, | |
| 182 | <option>null</option>.</para></listitem> | |
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183 | </varlistentry> |
| 184 | <varlistentry> | |
| 185 | <term><option>--log-level=</option></term> | |
| 186 | ||
| 187 | <listitem><para>Set log level. As | |
| 188 | argument this accepts a numerical log | |
| 189 | level or the well-known <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 190 | symbolic names (lowercase): | |
| 191 | <option>emerg</option>, | |
| 192 | <option>alert</option>, | |
| 193 | <option>crit</option>, | |
| 194 | <option>err</option>, | |
| 195 | <option>warning</option>, | |
| 196 | <option>notice</option>, | |
| 197 | <option>info</option>, | |
| 198 | <option>debug</option>.</para></listitem> | |
| 199 | </varlistentry> | |
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200 | <varlistentry> |
| 201 | <term><option>--log-color=</option></term> | |
| 202 | ||
| 203 | <listitem><para>Highlight important | |
| 204 | log messages. Argument is a boolean | |
| 205 | value. If the argument is omitted it | |
| 206 | defaults to | |
| 207 | <option>true</option>.</para></listitem> | |
| 208 | </varlistentry> | |
| 209 | <varlistentry> | |
| 210 | <term><option>--log-location=</option></term> | |
| 211 | ||
| 212 | <listitem><para>Include code location | |
| 213 | in log messages. This is mostly | |
| 214 | relevant for debugging | |
| 215 | purposes. Argument is a boolean | |
| 216 | value. If the argument is omitted | |
| 217 | it defaults to | |
| 218 | <option>true</option>.</para></listitem> | |
| 219 | </varlistentry> | |
| 2218198b LP |
220 | </variablelist> |
| 221 | </refsect1> | |
| 222 | ||
| 99ffae46 LP |
223 | <refsect1> |
| 224 | <title>Concepts</title> | |
| 225 | ||
| 226 | <para>systemd provides a dependency system between | |
| 227 | various entities called "units". Units encapsulate | |
| 228 | various objects that are relevant for system boot-up | |
| 229 | and maintainance. The majority of units are configured | |
| 230 | in unit configuration files, whose syntax and basic | |
| 231 | set of options is described in | |
| 232 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 233 | however some are created automatically from other | |
| 234 | configuration or dynamically from system state. Units | |
| 235 | may be active (meaning started, bound, plugged in, ... | |
| 236 | depending on the unit type), or inactive (meaning | |
| dccb2600 | 237 | stopped, unbound, unplugged, ...), as well as in the |
| 99ffae46 LP |
238 | process of being activated or deactivated, |
| 239 | i.e. between the two states. The following unit types | |
| 240 | are available:</para> | |
| 241 | ||
| 242 | <orderedlist> | |
| 243 | <listitem><para>Service units, which control | |
| 244 | daemons and the processes they consist of. For | |
| 245 | details see | |
| 246 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 247 | ||
| 248 | <listitem><para>Socket units, which | |
| 249 | encapsulate local IPC or network sockets in | |
| 250 | the system, useful for socket-based | |
| 251 | activation. For details about socket units see | |
| 252 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 253 | for details on socket-based activation and | |
| 254 | other forms of activation, see | |
| 255 | <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem> | |
| 256 | ||
| 257 | <listitem><para>Target units are useful to | |
| 258 | group units, or provide well-known | |
| 259 | synchronization points during boot-up, see | |
| 260 | <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 261 | ||
| 262 | <listitem><para>Device units expose kernel | |
| 263 | devices in systemd and may be used to | |
| 264 | implement device-based activation. For details | |
| 265 | see | |
| 266 | <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 267 | ||
| 268 | <listitem><para>Mount units control mount | |
| 269 | points in the file system, for details see | |
| 270 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 271 | ||
| 272 | <listitem><para>Automount units provide | |
| 273 | automount capabilities, for on-demand mounting | |
| 274 | of file systems as well as parallelized | |
| 275 | boot-up. See | |
| 276 | <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 277 | ||
| 278 | <listitem><para>Snapshot units can be used to | |
| 279 | temporarily save the state of the set of | |
| 280 | systemd units, which later may be restored by | |
| 281 | activating the saved snapshot unit. For more | |
| 282 | information see | |
| 7461d1b7 | 283 | <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> |
| 99ffae46 LP |
284 | |
| 285 | <listitem><para>Timer units are useful for | |
| 286 | triggering activation of other units based on | |
| 287 | timers. You may find details in | |
| 288 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 289 | ||
| 290 | <listitem><para>Swap units are very similar to | |
| 291 | mount units and encapsulated memory swap | |
| 292 | partitions or files of the operating | |
| 293 | systemd. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 294 | ||
| 295 | <listitem><para>Path units may be used | |
| dccb2600 | 296 | to activate other services when file system |
| 99ffae46 LP |
297 | objects change or are modified. See |
| 298 | <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
| 299 | ||
| 300 | </orderedlist> | |
| 301 | ||
| 302 | <para>Units are named as their configuration | |
| 303 | files. Some units have special semantics. A detailed | |
| 304 | list you may find in | |
| 305 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> | |
| 306 | ||
| 307 | <para>On boot systemd activates the target unit | |
| dccb2600 | 308 | <filename>default.target</filename> whose job is to |
| 99ffae46 LP |
309 | activate on-boot services and other on-boot units by |
| 310 | pulling them in via dependencies. Usually the unit | |
| 311 | name is just an alias (symlink) for either | |
| 312 | <filename>graphical.target</filename> (for | |
| 313 | fully-featured boots into the UI) or | |
| 314 | <filename>multi-user.target</filename> (for limited | |
| 315 | console-only boots for use in embedded or server | |
| 316 | environments, or similar; a subset of | |
| 317 | graphical.target). However it is at the discretion of | |
| 318 | the administrator to configure it as an alias to any | |
| 319 | other target unit. See | |
| 320 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
| 321 | for details about these target units.</para> | |
| 322 | ||
| dccb2600 | 323 | <para>Processes systemd spawns are placed in |
| 59a3e1bc LP |
324 | individual Linux control groups named after the unit |
| 325 | which they belong to in the private systemd | |
| 326 | hierarchy. (see <ulink | |
| 327 | url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink> | |
| 328 | for more information about control groups, or short | |
| 329 | "cgroups"). systemd uses this to effectively keep | |
| 330 | track of processes. Control group information is | |
| 331 | maintained in the kernel, and is accessible via the | |
| 332 | file system hierarchy (beneath | |
| 333 | <filename>/cgroup/systemd/</filename>), or in tools | |
| 334 | such as | |
| 335 | <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
| 336 | (<command>ps xawf -eo pid,user,cgroup,args</command> | |
| 337 | is particularly useful to list all processes and the | |
| 338 | systemd units they belong to.).</para> | |
| 339 | ||
| 340 | <para>systemd is compatible with the SysV init system | |
| 341 | to a large degree: SysV init scripts are supported and | |
| 342 | simply read as an alternative (though limited) | |
| 343 | configuration file format. The SysV | |
| 344 | <filename>/dev/initctl</filename> interface is | |
| dccb2600 OÇ |
345 | provided, and compatibility implementations of the |
| 346 | various SysV client tools are available. In addition to | |
| 347 | that, various established Unix functionality such as | |
| 59a3e1bc LP |
348 | <filename>/etc/fstab</filename> or the |
| 349 | <filename>utmp</filename> database are | |
| 350 | supported.</para> | |
| 351 | ||
| 352 | <para>systemd has a minimal transaction system: if a | |
| 353 | unit is requested to start up or shut down it will add | |
| 354 | it and all its dependencies to a temporary | |
| 355 | transaction. Then, it will verify if the transaction | |
| 356 | is consistent (i.e. whether the ordering of all units | |
| 357 | is cycle-free). If it is not, systemd will try to fix | |
| 358 | it up, and removes non-essential jobs from the | |
| 359 | transaction that might remove the loop. Also, systemd | |
| 360 | tries to suppress non-essential jobs in the | |
| 361 | transaction that would stop a running service. Finally | |
| 362 | it is checked whether the jobs of the transaction | |
| 363 | contradict jobs that have already been queued, and | |
| 364 | optionally the transaction is aborted then. If all | |
| 365 | worked out and the transaction is consistent and | |
| 366 | minimized in its impact it is merged with all already | |
| 367 | outstanding jobs and added to the run | |
| 368 | queue. Effectively this means that before executing a | |
| 369 | requested operation, systemd will verify that it makes | |
| 370 | sense, fixing it if possible, and only failing if it | |
| 371 | really cannot work.</para> | |
| 372 | ||
| 373 | <para>Systemd contains native implementations of | |
| 374 | various tasks that need to be executed as part of the | |
| 375 | boot process. For example, it sets the host name or | |
| 376 | configures the loopback network device. It also sets | |
| 377 | up and mounts various API file systems, such as | |
| 378 | <filename>/sys</filename> or | |
| 379 | <filename>/proc</filename>.</para> | |
| 380 | ||
| 99ffae46 LP |
381 | <para>For more information about the concepts and |
| 382 | ideas behind systemd please refer to the <ulink | |
| 383 | url="http://0pointer.de/blog/projects/systemd.html">Original | |
| 59a3e1bc | 384 | Design Document</ulink>.</para> |
| 99ffae46 LP |
385 | </refsect1> |
| 386 | ||
| 160cd5c9 LP |
387 | <refsect1> |
| 388 | <title>Directories</title> | |
| 7874bcd6 LP |
389 | |
| 390 | <variablelist> | |
| 391 | <varlistentry> | |
| 392 | <term>System unit directories</term> | |
| 393 | ||
| 394 | <listitem><para>The systemd system | |
| 395 | manager reads unit configuration from | |
| 396 | various directories. Packages that | |
| 397 | want to install unit files shall place | |
| 398 | them in the directory returned by | |
| 399 | <command>pkg-config systemd | |
| 400 | --variable=systemdsystemunitdir</command>. Other | |
| 401 | directories checked are | |
| 402 | <filename>/usr/local/share/systemd/system</filename> | |
| 403 | and | |
| 404 | <filename>/usr/share/systemd/system</filename>. User | |
| 405 | configuration always takes | |
| 406 | precedence. <command>pkg-config | |
| 407 | systemd | |
| 408 | --variable=systemdsystemconfdir</command> | |
| 409 | returns the path of the system | |
| 410 | configuration directory. Packages | |
| af62c704 KS |
411 | should alter the content of these directories |
| 412 | only with the | |
| 7874bcd6 LP |
413 | <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
| 414 | tool.</para></listitem> | |
| 415 | </varlistentry> | |
| 416 | </variablelist> | |
| 417 | ||
| 418 | <variablelist> | |
| 419 | <varlistentry> | |
| 420 | <term>Session unit directories</term> | |
| 421 | ||
| 422 | <listitem><para>Similar rules apply | |
| 423 | for the session unit | |
| 424 | directories. However, here the <ulink | |
| 425 | url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG | |
| 426 | Base Directory specification</ulink> | |
| 427 | is followed to find | |
| 428 | units. Applications should place their | |
| 429 | unit files in the directory returned | |
| 430 | by <command>pkg-config systemd | |
| 431 | --variable=systemdsessionunitdir</command>. Global | |
| 432 | configuration is done in the | |
| 433 | directory reported by | |
| 434 | <command>pkg-config systemd | |
| 435 | --variable=systemdsessionconfdir</command>. The | |
| 436 | <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
| 437 | tool can handle both global (i.e. for | |
| 438 | all users) and private (for one user) | |
| 439 | enabling/disabling of | |
| 440 | units.</para></listitem> | |
| 441 | </varlistentry> | |
| 442 | </variablelist> | |
| 443 | ||
| 444 | <variablelist> | |
| 445 | <varlistentry> | |
| 446 | <term>SysV init scripts directory</term> | |
| 447 | ||
| 448 | <listitem><para>The location of the | |
| 449 | SysV init script directory varies | |
| 450 | between distributions. If systemd | |
| 451 | cannot find a native unit file for a | |
| af62c704 | 452 | requested service, it will look for a |
| 7874bcd6 LP |
453 | SysV init script of the same name |
| 454 | (with the | |
| 455 | <filename>.service</filename> suffix | |
| 456 | removed).</para></listitem> | |
| 457 | </varlistentry> | |
| 458 | </variablelist> | |
| 459 | ||
| 460 | <variablelist> | |
| 461 | <varlistentry> | |
| 462 | <term>SysV runlevel link farm directory</term> | |
| 463 | ||
| 464 | <listitem><para>The location of the | |
| 465 | SysV runlevel link farm directory | |
| 466 | varies between distributions. systemd | |
| 467 | will take the link farm into account | |
| 468 | when figuring out whether a service | |
| 469 | shall be enabled. Note that a service | |
| 470 | unit with a native unit configuration | |
| edb9aaa8 | 471 | file cannot be started by activating it |
| 7874bcd6 LP |
472 | in the SysV runlevel link |
| 473 | farm.</para></listitem> | |
| 474 | </varlistentry> | |
| 475 | </variablelist> | |
| 160cd5c9 LP |
476 | </refsect1> |
| 477 | ||
| 478 | <refsect1> | |
| 7874bcd6 | 479 | <title>Signals</title> |
| 160cd5c9 LP |
480 | |
| 481 | <variablelist> | |
| 482 | <varlistentry> | |
| 7874bcd6 LP |
483 | <term>SIGTERM</term> |
| 484 | ||
| 485 | <listitem><para>Upon receiving this | |
| 486 | signal the systemd system manager | |
| 487 | serializes its state, reexecutes | |
| 488 | itself and deserializes the saved | |
| 489 | state again. This is mostly equivalent | |
| 490 | to <command>systemctl | |
| 491 | daemon-reexec</command>.</para> | |
| 492 | ||
| 493 | <para>systemd session managers will | |
| 494 | start the | |
| 495 | <filename>exit.target</filename> unit | |
| 496 | when this signal is received. This is | |
| 497 | mostly equivalent to | |
| 498 | <command>systemctl --session start | |
| 499 | exit.target</command>.</para></listitem> | |
| 500 | </varlistentry> | |
| 501 | ||
| 502 | <varlistentry> | |
| 503 | <term>SIGINT</term> | |
| 504 | ||
| 505 | <listitem><para>Upon receiving this | |
| 506 | signal the systemd system manager will | |
| 507 | start the | |
| 508 | <filename>ctrl-alt-del.target</filename> unit. This | |
| 509 | is mostly equivalent to | |
| 510 | <command>systemctl start | |
| 511 | ctl-alt-del.target</command>.</para> | |
| 512 | ||
| 513 | <para>systemd session managers | |
| 514 | treat this signal the same way as | |
| 515 | SIGTERM.</para></listitem> | |
| 516 | </varlistentry> | |
| 517 | ||
| 518 | <varlistentry> | |
| 519 | <term>SIGWINCH</term> | |
| 520 | ||
| 521 | <listitem><para>When this signal is | |
| 522 | received the systemd system manager | |
| 523 | will start the | |
| 524 | <filename>kbrequest.target</filename> | |
| 525 | unit. This is mostly equivalent to | |
| 526 | <command>systemctl start | |
| 527 | kbrequest.target</command>.</para> | |
| 528 | ||
| 529 | <para>This signal is ignored by | |
| 530 | systemd session | |
| 531 | managers.</para></listitem> | |
| 532 | </varlistentry> | |
| 533 | ||
| 534 | <varlistentry> | |
| 535 | <term>SIGPWR</term> | |
| 536 | ||
| 537 | <listitem><para>When this signal is | |
| 538 | received the systemd manager | |
| 539 | will start the | |
| 540 | <filename>sigpwr.target</filename> | |
| 541 | unit. This is mostly equivalent to | |
| 542 | <command>systemctl start | |
| 543 | sigpwr.target</command>.</para></listitem> | |
| 544 | </varlistentry> | |
| 545 | ||
| 546 | <varlistentry> | |
| 547 | <term>SIGUSR1</term> | |
| 548 | ||
| 549 | <listitem><para>When this signal is | |
| 550 | received the systemd manager will try | |
| 551 | to reconnect to the D-Bus | |
| 552 | bus.</para></listitem> | |
| 553 | </varlistentry> | |
| 554 | ||
| 555 | <varlistentry> | |
| 556 | <term>SIGUSR2</term> | |
| 557 | ||
| 558 | <listitem><para>When this signal is | |
| 559 | received the systemd manager will log | |
| 560 | its complete state in human readable | |
| 561 | form. The data logged is the same as | |
| 562 | printed by <command>systemctl | |
| 563 | dump</command>.</para></listitem> | |
| 564 | </varlistentry> | |
| 565 | ||
| 566 | <varlistentry> | |
| 567 | <term>SIGHUP</term> | |
| 568 | ||
| 569 | <listitem><para>Reloads the complete | |
| 570 | daemon configuration. This is mostly | |
| 571 | equivalent to <command>systemctl | |
| 572 | daemon-reload</command>.</para></listitem> | |
| 573 | </varlistentry> | |
| 574 | ||
| 575 | <varlistentry> | |
| 576 | <term>SIGRTMIN+0</term> | |
| 577 | ||
| 578 | <listitem><para>Enters default mode, starts the | |
| 579 | <filename>default.target</filename> | |
| 580 | unit. This is mostly equivalent to | |
| 581 | <command>systemctl start | |
| 582 | default.target</command>.</para></listitem> | |
| 583 | </varlistentry> | |
| 584 | ||
| 585 | <varlistentry> | |
| 586 | <term>SIGRTMIN+1</term> | |
| 587 | ||
| 588 | <listitem><para>Enters rescue mode, | |
| 589 | starts the | |
| 590 | <filename>rescue.target</filename> | |
| 591 | unit. This is mostly equivalent to | |
| 592 | <command>systemctl isolate | |
| 593 | rescue.target</command>.</para></listitem> | |
| 594 | </varlistentry> | |
| 160cd5c9 | 595 | |
| 7874bcd6 LP |
596 | <varlistentry> |
| 597 | <term>SIGRTMIN+2</term> | |
| 598 | ||
| 599 | <listitem><para>Enters emergency mode, | |
| 600 | starts the | |
| 601 | <filename>emergency.service</filename> | |
| 602 | unit. This is mostly equivalent to | |
| 603 | <command>systemctl isolate | |
| 604 | emergency.service</command>.</para></listitem> | |
| 605 | </varlistentry> | |
| 606 | ||
| 607 | <varlistentry> | |
| 608 | <term>SIGRTMIN+3</term> | |
| 609 | ||
| 610 | <listitem><para>Halts the machine, | |
| 611 | starts the | |
| 612 | <filename>halt.target</filename> | |
| 613 | unit. This is mostly equivalent to | |
| 614 | <command>systemctl start | |
| 615 | halt.target</command>.</para></listitem> | |
| 616 | </varlistentry> | |
| 617 | ||
| 618 | <varlistentry> | |
| 619 | <term>SIGRTMIN+4</term> | |
| 620 | ||
| 621 | <listitem><para>Powers off the machine, | |
| 622 | starts the | |
| 623 | <filename>poweroff.target</filename> | |
| 624 | unit. This is mostly equivalent to | |
| 625 | <command>systemctl start | |
| 626 | poweroff.target</command>.</para></listitem> | |
| 627 | </varlistentry> | |
| 628 | ||
| 629 | <varlistentry> | |
| 630 | <term>SIGRTMIN+5</term> | |
| 631 | ||
| 632 | <listitem><para>Reboots the machine, | |
| 633 | starts the | |
| 634 | <filename>reboot.target</filename> | |
| 635 | unit. This is mostly equivalent to | |
| 636 | <command>systemctl start | |
| 637 | reboot.target</command>.</para></listitem> | |
| 160cd5c9 LP |
638 | </varlistentry> |
| 639 | </variablelist> | |
| 640 | </refsect1> | |
| 641 | ||
| 7874bcd6 LP |
642 | <refsect1> |
| 643 | <title>Environment</title> | |
| 644 | ||
| 645 | <variablelist> | |
| 646 | <varlistentry> | |
| 647 | <term><varname>$SYSTEMD_LOG_LEVEL</varname></term> | |
| 648 | <listitem><para>systemd reads the | |
| 649 | log level from this environment | |
| 436c44a5 | 650 | variable. This can be overridden with |
| 7874bcd6 LP |
651 | <option>--log-level=</option>.</para></listitem> |
| 652 | </varlistentry> | |
| 653 | ||
| 654 | <varlistentry> | |
| 655 | <term><varname>$SYSTEMD_LOG_TARGET</varname></term> | |
| 656 | <listitem><para>systemd reads the | |
| 657 | log target from this environment | |
| 436c44a5 | 658 | variable. This can be overridden with |
| 7874bcd6 LP |
659 | <option>--log-target=</option>.</para></listitem> |
| 660 | </varlistentry> | |
| 661 | ||
| 662 | <varlistentry> | |
| 663 | <term><varname>$SYSTEMD_LOG_COLOR</varname></term> | |
| 664 | <listitem><para>Controls whether | |
| 665 | systemd highlights important log | |
| 436c44a5 | 666 | messages. This can be overridden with |
| 7874bcd6 LP |
667 | <option>--log-color=</option>.</para></listitem> |
| 668 | </varlistentry> | |
| 669 | ||
| 670 | <varlistentry> | |
| 671 | <term><varname>$SYSTEMD_LOG_LOCATION</varname></term> | |
| 672 | <listitem><para>Controls whether | |
| 673 | systemd prints the code location along | |
| 674 | with log messages. This can be | |
| 436c44a5 | 675 | overridden with |
| 7874bcd6 LP |
676 | <option>--log-location=</option>.</para></listitem> |
| 677 | </varlistentry> | |
| 678 | ||
| 679 | <varlistentry> | |
| 680 | <term><varname>$XDG_CONFIG_HOME</varname></term> | |
| 681 | <term><varname>$XDG_CONFIG_DIRS</varname></term> | |
| 682 | <term><varname>$XDG_DATA_HOME</varname></term> | |
| 683 | <term><varname>$XDG_DATA_DIRS</varname></term> | |
| 684 | ||
| 685 | <listitem><para>The systemd session | |
| 686 | manager uses these variables in | |
| 687 | accordance to the <ulink | |
| 688 | url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG | |
| 689 | Base Directory specification</ulink> | |
| 690 | to find its configuration.</para></listitem> | |
| 691 | </varlistentry> | |
| 692 | ||
| 693 | <varlistentry> | |
| 694 | <term><varname>$SYSTEMD_UNIT_PATH</varname></term> | |
| 695 | ||
| 696 | <listitem><para>Controls where systemd | |
| 697 | looks for unit | |
| 698 | files.</para></listitem> | |
| 699 | </varlistentry> | |
| 700 | ||
| 701 | <varlistentry> | |
| 702 | <term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term> | |
| 703 | ||
| 704 | <listitem><para>Controls where systemd | |
| 705 | looks for SysV init scripts.</para></listitem> | |
| 706 | </varlistentry> | |
| 707 | ||
| 708 | <varlistentry> | |
| 709 | <term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term> | |
| 710 | ||
| 711 | <listitem><para>Controls where systemd | |
| 712 | looks for SysV init script runlevel link | |
| 713 | farms.</para></listitem> | |
| 714 | </varlistentry> | |
| 715 | ||
| 716 | <varlistentry> | |
| 717 | <term><varname>$LISTEN_PID</varname></term> | |
| 718 | <term><varname>$LISTEN_FDS</varname></term> | |
| 719 | ||
| 720 | <listitem><para>Set by systemd for | |
| 721 | supervised processes during | |
| 722 | socket-based activation. See | |
| 723 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 724 | for more information. | |
| 725 | </para></listitem> | |
| 726 | </varlistentry> | |
| 727 | ||
| 728 | <varlistentry> | |
| 729 | <term><varname>$NOTIFY_SOCKET</varname></term> | |
| 730 | ||
| 731 | <listitem><para>Set by systemd for | |
| 732 | supervised processes for status and | |
| 733 | start-up completion notification. See | |
| 734 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 735 | for more information. | |
| 736 | </para></listitem> | |
| 737 | </varlistentry> | |
| 738 | </variablelist> | |
| 739 | </refsect1> | |
| 160cd5c9 | 740 | |
| f3e219a2 LP |
741 | <refsect1> |
| 742 | <title>Kernel Command Line</title> | |
| 743 | ||
| 744 | <para>When run as system instance systemd parses a few kernel command line arguments:</para> | |
| 745 | ||
| 746 | <variablelist> | |
| 747 | <varlistentry> | |
| 748 | <term><varname>systemd.unit=</varname></term> | |
| 749 | ||
| 750 | <listitem><para>Overrides the unit to | |
| 751 | activate on boot. Defaults to | |
| 752 | <filename>default.target</filename>. This | |
| 753 | may be used to temporarily boot into a | |
| 754 | different boot unit, for example | |
| 755 | <filename>rescue.target</filename> or | |
| 756 | <filename>emergency.service</filename>. See | |
| 757 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
| 758 | for details about these | |
| 759 | units.</para></listitem> | |
| 760 | </varlistentry> | |
| 761 | ||
| 762 | <varlistentry> | |
| 763 | <term><varname>systemd.log_target=</varname></term> | |
| 764 | <term><varname>systemd.log_level=</varname></term> | |
| 765 | <term><varname>systemd.log_color=</varname></term> | |
| 766 | <term><varname>systemd.log_location=</varname></term> | |
| 767 | ||
| 768 | <listitem><para>Controls log output, | |
| 769 | with the same effect as the | |
| 770 | <varname>$SYSTEMD_LOG_TARGET</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>, <varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LOCATION</varname> | |
| 771 | environment variables described above.</para></listitem> | |
| 772 | </varlistentry> | |
| 773 | ||
| 774 | <varlistentry> | |
| 775 | <term><varname>systemd.dump_core=</varname></term> | |
| 776 | ||
| 777 | <listitem><para>Takes a boolean | |
| 778 | argument. If <option>true</option> | |
| 779 | systemd dumps core when it | |
| 780 | crashes. Otherwise no core dump is | |
| 781 | created. Defaults to | |
| 782 | <option>true</option>.</para></listitem> | |
| 783 | </varlistentry> | |
| 784 | ||
| 785 | <varlistentry> | |
| 786 | <term><varname>systemd.crash_shell=</varname></term> | |
| 787 | ||
| 788 | <listitem><para>Takes a boolean | |
| 789 | argument. If <option>true</option> | |
| 790 | systemd spawns a shell when it | |
| 791 | crashes. Otherwise no core dump is | |
| 792 | created. Defaults to | |
| 793 | <option>false</option>, for security | |
| 794 | reasons, as the shell is not protected | |
| 795 | by any password | |
| 796 | authentication.</para></listitem> | |
| 797 | </varlistentry> | |
| 798 | ||
| 799 | <varlistentry> | |
| 800 | <term><varname>systemd.crash_chvt=</varname></term> | |
| 801 | ||
| 802 | <listitem><para>Takes an integer | |
| 803 | argument. If positive systemd | |
| 804 | activates the specified virtual | |
| 805 | terminal when it crashes. Defaults to | |
| 806 | <literal>-1</literal>.</para></listitem> | |
| 807 | </varlistentry> | |
| 808 | ||
| 809 | <varlistentry> | |
| 810 | <term><varname>systemd.show_status=</varname></term> | |
| 811 | ||
| 812 | <listitem><para>Takes a boolean | |
| 813 | argument. If <option>true</option> | |
| 814 | shows terse service status updates on | |
| 815 | the console during bootup. Defaults to | |
| 816 | <option>true</option>.</para></listitem> | |
| 817 | </varlistentry> | |
| 818 | ||
| 819 | </variablelist> | |
| 820 | </refsect1> | |
| 821 | ||
| 2218198b LP |
822 | <refsect1> |
| 823 | <title>Sockets and FIFOs</title> | |
| 824 | ||
| 825 | <variablelist> | |
| 826 | <varlistentry> | |
| 827 | <term><filename>@/org/freedesktop/systemd1/notify</filename></term> | |
| 828 | ||
| 829 | <listitem><para>Daemon status | |
| 830 | notification socket. This is an AF_UNIX | |
| 831 | datagram socket in the Linux abstract | |
| 832 | namespace, and is used to implement | |
| 833 | the daemon notification logic as | |
| 834 | implemented by | |
| 835 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> | |
| 836 | ||
| 837 | </varlistentry> | |
| 838 | ||
| 839 | <varlistentry> | |
| 840 | <term><filename>@/org/freedesktop/systemd1/logger</filename></term> | |
| 841 | ||
| 842 | <listitem><para>Used internally by the | |
| 843 | <filename>systemd-logger.service</filename> | |
| 844 | unit to connect STDOUT and/or STDERR | |
| 845 | of spawned processes to | |
| 846 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
| 847 | or the kernel log buffer. This is an | |
| 848 | AF_UNIX stream socket in the Linux | |
| 849 | abstract namespace.</para></listitem> | |
| 850 | </varlistentry> | |
| 851 | ||
| 852 | <varlistentry> | |
| 853 | <term><filename>@/org/freedesktop/systemd1/private</filename></term> | |
| 854 | ||
| 855 | <listitem><para>Used internally as | |
| 856 | communication channel between | |
| 857 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
| 858 | and the systemd process. This is an | |
| 859 | AF_UNIX stream socket in the Linux | |
| 860 | abstract namespace. This interface is | |
| 861 | private to systemd and should not be | |
| 862 | used in external | |
| 863 | projects.</para></listitem> | |
| 864 | </varlistentry> | |
| 865 | ||
| 866 | <varlistentry> | |
| 867 | <term><filename>/dev/initctl</filename></term> | |
| 868 | ||
| 869 | <listitem><para>Limited compatibility | |
| 870 | support for the SysV client interface, | |
| 871 | as implemented by the | |
| 872 | <filename>systemd-initctl.service</filename> | |
| 873 | unit. This is a named pipe in the file | |
| 874 | system. This interface is obsolete and | |
| 875 | should not be used in new | |
| 876 | applications.</para></listitem> | |
| 877 | </varlistentry> | |
| 878 | </variablelist> | |
| 9e632bf7 LP |
879 | </refsect1> |
| 880 | ||
| 9e632bf7 LP |
881 | <refsect1> |
| 882 | <title>See Also</title> | |
| 883 | <para> | |
| 7874bcd6 LP |
884 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| 885 | <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
| 886 | <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
| 887 | <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
| 9e632bf7 | 888 | <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| 7874bcd6 LP |
889 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| 890 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 891 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
| 892 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
| 9e632bf7 LP |
893 | </para> |
| 894 | </refsect1> | |
| 895 | ||
| 896 | </refentry> |