systemd.xml 24 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625
  1. <?xml version="1.0" encoding="ISO-8859-1"?>
  2. <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  3. "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  4. <!ENTITY % general-entities SYSTEM "../general.ent">
  5. %general-entities;
  6. ]>
  7. <sect1 id="ch-system-systemd" role="wrap">
  8. <?dbhtml filename="systemd.html"?>
  9. <sect1info condition="script">
  10. <productname>systemd</productname>
  11. <productnumber>&systemd-version;</productnumber>
  12. <address>&systemd-url;</address>
  13. </sect1info>
  14. <title>Systemd-&systemd-version;</title>
  15. <indexterm zone="ch-system-systemd">
  16. <primary sortas="a-Systemd">Systemd</primary>
  17. </indexterm>
  18. <sect2 role="package">
  19. <title/>
  20. <para>The Systemd package contains programs for controlling the startup,
  21. running, and shutdown of the system.</para>
  22. <segmentedlist>
  23. <segtitle>&buildtime;</segtitle>
  24. <segtitle>&diskspace;</segtitle>
  25. <seglistitem>
  26. <seg>&systemd-ch6-sbu;</seg>
  27. <seg>&systemd-ch6-du;</seg>
  28. </seglistitem>
  29. </segmentedlist>
  30. </sect2>
  31. <sect2 role="installation">
  32. <title>Installation of Systemd</title>
  33. <note><para>If systemd is not desired at all, it can be skipped. However a
  34. udev replacement must be installed. See the hint at <ulink
  35. url="http://www.linuxfromscratch.org/hints/downloads/files/eudev-alt-hint.txt"/>
  36. to find procedures to install
  37. <application>eudev</application>.</para></note>
  38. <para>First, create a file to allow Systemd to build when using Util-Linux
  39. built in Chapter 5:</para>
  40. <screen><userinput remap="pre">cat &gt; config.cache &lt;&lt; "EOF"
  41. <literal>KILL=/bin/kill
  42. HAVE_BLKID=1
  43. BLKID_LIBS="-lblkid"
  44. BLKID_CFLAGS="-I/tools/include/blkid"</literal>
  45. EOF</userinput></screen>
  46. <para>Aditionally, fix a build error when using Util-Linux built in
  47. Chapter 5:</para>
  48. <screen><userinput remap="pre">sed -i "s:blkid/::" $(grep -rl "blkid/blkid.h")</userinput></screen>
  49. <para>Apply a patch so that compat <command>pkg-config</command> files get
  50. installed without installing compat libs which are useless on LFS:</para>
  51. <screen><userinput remap="pre">patch -Np1 -i ../&systemd-compat-patch;</userinput></screen>
  52. <para>Prepare Systemd for compilation:</para>
  53. <screen><userinput remap="configure">./configure --prefix=/usr \
  54. --sysconfdir=/etc \
  55. --localstatedir=/var \
  56. --config-cache \
  57. --with-rootprefix= \
  58. --with-rootlibdir=/lib \
  59. --enable-split-usr \
  60. --disable-gudev \
  61. --without-python \
  62. --docdir=/usr/share/doc/systemd-&systemd-version; \
  63. --with-dbuspolicydir=/etc/dbus-1/system.d \
  64. --with-dbusinterfacedir=/usr/share/dbus-1/interfaces \
  65. --with-dbussessionservicedir=/usr/share/dbus-1/services \
  66. --with-dbussystemservicedir=/usr/share/dbus-1/system-services</userinput></screen>
  67. <variablelist>
  68. <title>The meaning of the configure options:</title>
  69. <varlistentry>
  70. <term><parameter>--config-cache</parameter></term>
  71. <listitem>
  72. <para>This switch tells the build system to use
  73. the <filename>config.cache</filename> file which
  74. was created earlier.</para>
  75. </listitem>
  76. </varlistentry>
  77. <varlistentry>
  78. <term><parameter>--with-root*</parameter></term>
  79. <listitem>
  80. <para>These switches ensure that core programs and
  81. shared libraries are installed in the subdirectories
  82. of the root partition.</para>
  83. </listitem>
  84. </varlistentry>
  85. <varlistentry>
  86. <term><parameter>--enable-split-usr</parameter></term>
  87. <listitem>
  88. <para>This switch ensures that Systemd will work on
  89. systems where /bin, /lib and /sbin directories are not
  90. symlinks to their /usr counterparts.</para>
  91. </listitem>
  92. </varlistentry>
  93. <varlistentry>
  94. <term><parameter>--disable-gudev --without-python</parameter></term>
  95. <listitem>
  96. <para>These switches disable optional features because
  97. LFS does not provide their dependencies.</para>
  98. </listitem>
  99. </varlistentry>
  100. <varlistentry>
  101. <term><parameter>--with-dbus*</parameter></term>
  102. <listitem>
  103. <para>These switches ensure that D-Bus configuratil files
  104. get installed in the correct locations.</para>
  105. </listitem>
  106. </varlistentry>
  107. </variablelist>
  108. <para>Compile the package:</para>
  109. <screen><userinput remap="make">make LIBRARY_PATH=/tools/lib</userinput></screen>
  110. <para>First prevent few broken test cases from running:</para>
  111. <screen><userinput remap="test">sed -e "s:test/udev-test.pl::g" \
  112. -e "s:test-bus-cleanup\$(EXEEXT) ::g" \
  113. -e "s:test-bus-gvariant\$(EXEEXT) ::g" \
  114. -i Makefile</userinput></screen>
  115. <para>To test the results, issue:</para>
  116. <screen><userinput remap="test">make -k check</userinput></screen>
  117. <para>Note that some tests might fail because the test are being run in a
  118. chroot environment. For full test coverage, the test suite should be run
  119. from a system booted using Systemd.</para>
  120. <para>Install the package:</para>
  121. <screen><userinput remap="install">make LD_LIBRARY_PATH=/tools/lib install</userinput></screen>
  122. <para>Move NSS myhostname library to <filename
  123. class="directory">/lib</filename>:</para>
  124. <screen><userinput remap="install">mv -v /usr/lib/libnss_myhostname.so.2 /lib</userinput></screen>
  125. <para>Remove an unnecessary directory:</para>
  126. <screen><userinput remap="install">rm -rfv /usr/lib/rpm</userinput></screen>
  127. <para>Create the Sysvinit compatibility symlinks, and move some man pages
  128. and a library that conflict with <xref linkend="ch-system-sysvinit"/> so
  129. both systems can be installed side-by-side:</para>
  130. <screen><userinput remap="install">for tool in runlevel reboot shutdown poweroff halt telinit; do
  131. ln -sfv ../bin/systemctl /sbin/${tool}-systemd
  132. mv -v /usr/share/man/man8/${tool}.8 /usr/share/man/man8/${tool}-systemd.8
  133. done
  134. ln -sfv ../lib/systemd/systemd /sbin/init-systemd
  135. mv -v /etc/init.d /etc/init.d-systemd</userinput></screen>
  136. <para>Remove a reference to a non-existent group:</para>
  137. <screen><userinput remap="install">sed -i "s:0775 root lock:0755 root root:g" /usr/lib/tmpfiles.d/legacy.conf</userinput></screen>
  138. <para>Create the <filename>/etc/machine-id</filename> file needed by
  139. Journald:</para>
  140. <screen><userinput remap="install">systemd-machine-id-setup</userinput></screen>
  141. <para>Finally install some LFS specific udev rules:</para>
  142. <screen><userinput remap="install">tar -xf ../&udev-lfs-version;.tar.bz2
  143. make -f &udev-lfs-version;/Makefile.lfs install</userinput></screen>
  144. </sect2>
  145. <sect2 id="contents-systemd" role="content">
  146. <title>Contents of Systemd</title>
  147. <segmentedlist>
  148. <segtitle>Installed programs</segtitle>
  149. <segtitle>Installed libraries</segtitle>
  150. <segtitle>Installed directories</segtitle>
  151. <seglistitem>
  152. <seg>bootctl, busctl, halt, hostnamectl, init, journalctl, kernel-install,
  153. localectl, loginctl, machinectl, poweroff, reboot, runlevel, shutdown,
  154. systemctl, systemd-analyze, systemd-ask-password, systemd-cat, systemd-cgls,
  155. systemd-cgtop, systemd-coredumpctl, systemd-delta, systemd-detect-virt,
  156. systemd-inhibit, systemd-machine-id-setup, systemd-notify, systemd-nspawn,
  157. systemd-run, systemd-stdio-bridge, systemd-tmpfiles, systemd-tty-ask-password-agent,
  158. telinit, timedatectl, and udevadm</seg>
  159. <seg>libnss_myhostname.so.2, libsystemd.so, libudev.so</seg>
  160. <seg>/etc/binfmt.d, /etc/init.d, /etc/kernel, /etc/modules-load.d,
  161. /etc/sysctl.d, /etc/systemd, /etc/tmpfiles.d, /etc/udev,
  162. /etc/xdg/systemd, /lib/systemd, /lib/udev, /usr/include/systemd,
  163. /usr/lib/binfmt.d, /usr/lib/kernel, /usr/lib/modules-load.d,
  164. /usr/lib/sysctl.d, /usr/lib/systemd, /usr/lib/tmpfiles.d,
  165. /usr/share/doc/systemd-&systemd-version;, /usr/share/systemd,
  166. /var/lib/systemd, /var/log/journal</seg>
  167. </seglistitem>
  168. </segmentedlist>
  169. <variablelist>
  170. <bridgehead renderas="sect3">Short Descriptions</bridgehead>
  171. <?dbfo list-presentation="list"?>
  172. <?dbhtml list-presentation="table"?>
  173. <varlistentry id="bootctl">
  174. <term><command>bootctl</command></term>
  175. <listitem>
  176. <para>used to query the firmware and boot manager settings.</para>
  177. <indexterm zone="ch-system-systemd bootctl">
  178. <primary sortas="b-bootctl">bootctl</primary>
  179. </indexterm>
  180. </listitem>
  181. </varlistentry>
  182. <varlistentry id="busctl">
  183. <term><command>busctl</command></term>
  184. <listitem>
  185. <para>used to introspect and monitor the D-Bus bus.</para>
  186. <indexterm zone="ch-system-systemd busctl">
  187. <primary sortas="b-busctl">busctl</primary>
  188. </indexterm>
  189. </listitem>
  190. </varlistentry>
  191. <varlistentry id="halt">
  192. <term><command>halt</command></term>
  193. <listitem>
  194. <para>Normally invokes <command>shutdown</command> with the
  195. <parameter>-h</parameter> option, except when already in run-level 0,
  196. then it tells the kernel to halt the system; it notes in the
  197. file <filename>/var/log/wtmp</filename> that the system is being
  198. brought down.</para>
  199. <indexterm zone="ch-system-systemd halt">
  200. <primary sortas="b-halt">halt</primary>
  201. </indexterm>
  202. </listitem>
  203. </varlistentry>
  204. <varlistentry id="hostnamectl">
  205. <term><command>hostnamectl</command></term>
  206. <listitem>
  207. <para>used to query and change the system hostname and related
  208. settings.</para>
  209. <indexterm zone="ch-system-systemd hostnamectl">
  210. <primary sortas="b-hostnamectl">hostnamectl</primary>
  211. </indexterm>
  212. </listitem>
  213. </varlistentry>
  214. <varlistentry id="init">
  215. <term><command>init</command></term>
  216. <listitem>
  217. <para>The first process to be started when the kernel has initialized
  218. the hardware which takes over the boot process and starts all the
  219. proceses it is instructed to.</para>
  220. <indexterm zone="ch-system-systemd init">
  221. <primary sortas="b-init">init</primary>
  222. </indexterm>
  223. </listitem>
  224. </varlistentry>
  225. <varlistentry id="journalctl">
  226. <term><command>journalctl</command></term>
  227. <listitem>
  228. <para>used to query the contents of the Systemd Journal.</para>
  229. <indexterm zone="ch-system-systemd journalctl">
  230. <primary sortas="b-journalctl">journalctl</primary>
  231. </indexterm>
  232. </listitem>
  233. </varlistentry>
  234. <varlistentry id="kernel-install">
  235. <term><command>kernel-install</command></term>
  236. <listitem>
  237. <para>used to add and remove kernel and initramfs images to and
  238. from /boot.</para>
  239. <indexterm zone="ch-system-systemd kernel-install">
  240. <primary sortas="b-kernel-install">kernel-install</primary>
  241. </indexterm>
  242. </listitem>
  243. </varlistentry>
  244. <varlistentry id="localectl">
  245. <term><command>localectl</command></term>
  246. <listitem>
  247. <para>used to query and change the system locale and keyboard layout
  248. settings.</para>
  249. <indexterm zone="ch-system-systemd localectl">
  250. <primary sortas="b-localectl">localectl</primary>
  251. </indexterm>
  252. </listitem>
  253. </varlistentry>
  254. <varlistentry id="loginctl">
  255. <term><command>loginctl</command></term>
  256. <listitem>
  257. <para>used to introspect and control the state of the Systemd Login
  258. Manager.</para>
  259. <indexterm zone="ch-system-systemd loginctl">
  260. <primary sortas="b-loginctl">loginctl</primary>
  261. </indexterm>
  262. </listitem>
  263. </varlistentry>
  264. <varlistentry id="machinectl">
  265. <term><command>machinectl</command></term>
  266. <listitem>
  267. <para>used to introspect and control the state of the Systemd Virtual
  268. Machine and Container Registration Manager</para>
  269. <indexterm zone="ch-system-systemd machinectl">
  270. <primary sortas="b-machinectl">machinectl</primary>
  271. </indexterm>
  272. </listitem>
  273. </varlistentry>
  274. <varlistentry id="poweroff">
  275. <term><command>poweroff</command></term>
  276. <listitem>
  277. <para>Tells the kernel to halt the system and switch off the computer
  278. (see <command>halt</command>).</para>
  279. <indexterm zone="ch-system-systemd poweroff">
  280. <primary sortas="b-poweroff">poweroff</primary>
  281. </indexterm>
  282. </listitem>
  283. </varlistentry>
  284. <varlistentry id="reboot">
  285. <term><command>reboot</command></term>
  286. <listitem>
  287. <para>Tells the kernel to reboot the system (see
  288. <command>halt</command>).</para>
  289. <indexterm zone="ch-system-systemd reboot">
  290. <primary sortas="b-reboot">reboot</primary>
  291. </indexterm>
  292. </listitem>
  293. </varlistentry>
  294. <varlistentry id="runlevel">
  295. <term><command>runlevel</command></term>
  296. <listitem>
  297. <para>Reports the previous and the current run-level, as noted in the
  298. last run-level record in <filename>/var/run/utmp</filename>.</para>
  299. <indexterm zone="ch-system-systemd runlevel">
  300. <primary sortas="b-runlevel">runlevel</primary>
  301. </indexterm>
  302. </listitem>
  303. </varlistentry>
  304. <varlistentry id="shutdown">
  305. <term><command>shutdown</command></term>
  306. <listitem>
  307. <para>Brings the system down in a secure way, signaling all processes
  308. and notifying all logged-in users.</para>
  309. <indexterm zone="ch-system-systemd shutdown">
  310. <primary sortas="b-shutdown">shutdown</primary>
  311. </indexterm>
  312. </listitem>
  313. </varlistentry>
  314. <varlistentry id="systemctl">
  315. <term><command>systemctl</command></term>
  316. <listitem>
  317. <para>used to introspect and control the state of the Systemd system and
  318. service manager.</para>
  319. <indexterm zone="ch-system-systemd systemctl">
  320. <primary sortas="b-systemctl">systemctl</primary>
  321. </indexterm>
  322. </listitem>
  323. </varlistentry>
  324. <varlistentry id="systemd-analyze">
  325. <term><command>systemd-analyze</command></term>
  326. <listitem>
  327. <para>used to determine system boot-up performance of the current boot.
  328. </para>
  329. <indexterm zone="ch-system-systemd systemd-analyze">
  330. <primary sortas="b-systemd-analyze">systemd-analyze</primary>
  331. </indexterm>
  332. </listitem>
  333. </varlistentry>
  334. <varlistentry id="systemd-ask-password">
  335. <term><command>systemd-ask-password</command></term>
  336. <listitem>
  337. <para>used to query a system password or passphrase from the user, using a
  338. question message specified on the command line.</para>
  339. <indexterm zone="ch-system-systemd systemd-ask-password">
  340. <primary sortas="b-systemd-ask-password">systemd-ask-password</primary>
  341. </indexterm>
  342. </listitem>
  343. </varlistentry>
  344. <varlistentry id="systemd-cat">
  345. <term><command>systemd-cat</command></term>
  346. <listitem>
  347. <para>used to connect STDOUT and STDERR of a process with the Journal.
  348. </para>
  349. <indexterm zone="ch-system-systemd systemd-cat">
  350. <primary sortas="b-systemd-cat">systemd-cat</primary>
  351. </indexterm>
  352. </listitem>
  353. </varlistentry>
  354. <varlistentry id="systemd-cgls">
  355. <term><command>systemd-cgls</command></term>
  356. <listitem>
  357. <para>recursively shows the contents of the selected Linux control group
  358. hierarchy in a tree.</para>
  359. <indexterm zone="ch-system-systemd systemd-cgls">
  360. <primary sortas="b-systemd-cgls">systemd-cgls</primary>
  361. </indexterm>
  362. </listitem>
  363. </varlistentry>
  364. <varlistentry id="systemd-cgtop">
  365. <term><command>systemd-cgtop</command></term>
  366. <listitem>
  367. <para>shows the top control groups of the local Linux control group hierarchy,
  368. ordered by their CPU, memory and disk I/O load.</para>
  369. <indexterm zone="ch-system-systemd systemd-cgtop">
  370. <primary sortas="b-systemd-cgtop">systemd-cgtop</primary>
  371. </indexterm>
  372. </listitem>
  373. </varlistentry>
  374. <varlistentry id="systemd-coredumpctl">
  375. <term><command>systemd-coredumpctl</command></term>
  376. <listitem>
  377. <para>used to retrieve coredumps from the Systemd Journal</para>
  378. <indexterm zone="ch-system-systemd systemd-coredumpctl">
  379. <primary sortas="b-systemd-coredumpctl">systemd-coredumpctl</primary>
  380. </indexterm>
  381. </listitem>
  382. </varlistentry>
  383. <varlistentry id="systemd-delta">
  384. <term><command>systemd-delta</command></term>
  385. <listitem>
  386. <para>used to identify and compare configuration files in
  387. <filename class="directory">/etc</filename> that override default
  388. counterparts in <filename class="directory">/usr</filename>.</para>
  389. <indexterm zone="ch-system-systemd systemd-delta">
  390. <primary sortas="b-systemd-delta">systemd-delta</primary>
  391. </indexterm>
  392. </listitem>
  393. </varlistentry>
  394. <varlistentry id="systemd-detect-virt">
  395. <term><command>systemd-detect-virt</command></term>
  396. <listitem>
  397. <para>detects execution in a virtualized environment.</para>
  398. <indexterm zone="ch-system-systemd systemd-detect-virt">
  399. <primary sortas="b-systemd-detect-virt">systemd-detect-virt</primary>
  400. </indexterm>
  401. </listitem>
  402. </varlistentry>
  403. <varlistentry id="systemd-inhibit">
  404. <term><command>systemd-inhibit</command></term>
  405. <listitem>
  406. <para>used to execute a program with a shutdown, sleep or idle inhibitor lock
  407. taken.</para>
  408. <indexterm zone="ch-system-systemd systemd-inhibit">
  409. <primary sortas="b-systemd-inhibit">systemd-inhibit</primary>
  410. </indexterm>
  411. </listitem>
  412. </varlistentry>
  413. <varlistentry id="systemd-machine-id-setup">
  414. <term><command>systemd-machine-id-setup</command></term>
  415. <listitem>
  416. <para>used by system installer tools to initialize the machine ID stored in
  417. <filename>/etc/machine-id</filename> at install time with a randomly
  418. generated ID.</para>
  419. <indexterm zone="ch-system-systemd systemd-machine-id-setup">
  420. <primary sortas="b-systemd-machine-id-setup">systemd-machine-id-setup</primary>
  421. </indexterm>
  422. </listitem>
  423. </varlistentry>
  424. <varlistentry id="systemd-notify">
  425. <term><command>systemd-notify</command></term>
  426. <listitem>
  427. <para>used by daemon scripts to notify the init system about status changes.
  428. </para>
  429. <indexterm zone="ch-system-systemd systemd-notify">
  430. <primary sortas="b-systemd-notify">systemd-notify</primary>
  431. </indexterm>
  432. </listitem>
  433. </varlistentry>
  434. <varlistentry id="systemd-nspawn">
  435. <term><command>systemd-nspawn</command></term>
  436. <listitem>
  437. <para>used to run a command or OS in a light-weight namespace container.</para>
  438. <indexterm zone="ch-system-systemd systemd-nspawn">
  439. <primary sortas="b-systemd-nspawn">systemd-nspawn</primary>
  440. </indexterm>
  441. </listitem>
  442. </varlistentry>
  443. <varlistentry id="systemd-run">
  444. <term><command>systemd-run</command></term>
  445. <listitem>
  446. <para>used to create and start a transient .service or a .scope unit and
  447. run the specified command in it.</para>
  448. <indexterm zone="ch-system-systemd systemd-run">
  449. <primary sortas="b-systemd-run">systemd-run</primary>
  450. </indexterm>
  451. </listitem>
  452. </varlistentry>
  453. <!-- <varlistentry id="systemd-stdio-bridge">
  454. <term><command>systemd-stdio-bridge</command></term>
  455. <listitem>
  456. <para>To be completed</para>
  457. <indexterm zone="ch-system-systemd systemd-stdio-bridge">
  458. <primary sortas="b-systemd-stdio-bridge">systemd-stdio-bridge</primary>
  459. </indexterm>
  460. </listitem>
  461. </varlistentry> -->
  462. <varlistentry id="systemd-tmpfiles">
  463. <term><command>systemd-tmpfiles</command></term>
  464. <listitem>
  465. <para>creates, deletes and cleans up volatile and temporary files and directories,
  466. based on the configuration file format and location specified in
  467. <filename class="directory">tmpfiles.d</filename> directories.</para>
  468. <indexterm zone="ch-system-systemd systemd-tmpfiles">
  469. <primary sortas="b-systemd-tmpfiles">systemd-tmpfiles</primary>
  470. </indexterm>
  471. </listitem>
  472. </varlistentry>
  473. <varlistentry id="systemd-tty-ask-password-agent">
  474. <term><command>systemd-tty-ask-password-agent</command></term>
  475. <listitem>
  476. <para>used to list or process pending Systemd password requests</para>
  477. <indexterm zone="ch-system-systemd systemd-tty-ask-password-agent">
  478. <primary sortas="b-systemd-tty-ask-password-agent">systemd-tty-ask-password-agent</primary>
  479. </indexterm>
  480. </listitem>
  481. </varlistentry>
  482. <varlistentry id="telinit">
  483. <term><command>telinit</command></term>
  484. <listitem>
  485. <para>Tells <command>init</command> which run-level to change to.</para>
  486. <indexterm zone="ch-system-systemd telinit">
  487. <primary sortas="b-telinit">telinit</primary>
  488. </indexterm>
  489. </listitem>
  490. </varlistentry>
  491. <varlistentry id="timedatectl">
  492. <term><command>timedatectl</command></term>
  493. <listitem>
  494. <para>used to query and change the system clock and its settings.
  495. </para>
  496. <indexterm zone="ch-system-systemd timedatectl">
  497. <primary sortas="b-timedatectl">timedatectl</primary>
  498. </indexterm>
  499. </listitem>
  500. </varlistentry>
  501. <varlistentry id="udevadm">
  502. <term><command>udevadm</command></term>
  503. <listitem>
  504. <para>Generic Udev administration tool: controls the udevd daemon,
  505. provides info from the Udev database, monitors uevents, waits for
  506. uevents to finish, tests Udev configuration, and triggers uevents
  507. for a given device.</para>
  508. <indexterm zone="ch-system-systemd udevadm">
  509. <primary sortas="b-udevadm">udevadm</primary>
  510. </indexterm>
  511. </listitem>
  512. </varlistentry>
  513. <varlistentry id="libsystemd">
  514. <term><filename class="libraryfile">libsystemd</filename></term>
  515. <listitem>
  516. <para>Systemd utility library.</para>
  517. <indexterm zone="ch-system-systemd libsystemd">
  518. <primary sortas="c-libsystemd">libsystemd</primary>
  519. </indexterm>
  520. </listitem>
  521. </varlistentry>
  522. <varlistentry id="libudev">
  523. <term><filename class="libraryfile">libudev</filename></term>
  524. <listitem>
  525. <para>A library to access Udev device information.</para>
  526. <indexterm zone="ch-system-systemd libudev">
  527. <primary sortas="c-libudev">libudev</primary>
  528. </indexterm>
  529. </listitem>
  530. </varlistentry>
  531. </variablelist>
  532. </sect2>
  533. </sect1>