BOOK/chapter08/systemd.xml

   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
   8 <sect1 id="ch-system-systemd" role="wrap" revision="systemd">
   9   <?dbhtml filename="systemd.html"?>
  10
  11   <sect1info condition="script">
  12     <productname>systemd</productname>
  13     <productnumber>&systemd-version;</productnumber>
  14     <address>&systemd-url;</address>
  15   </sect1info>
  16
  17   <title>Systemd-&systemd-version;</title>
  18
  19   <indexterm zone="ch-system-systemd">
  20     <primary sortas="a-systemd">systemd</primary>
  21   </indexterm>
  22
  23   <sect2 role="package">
  24     <title/>
  25
  26     <para>The systemd package contains programs for controlling the startup,
  27     running, and shutdown of the system.</para>
  28
  29     <segmentedlist>
  30       <segtitle>&buildtime;</segtitle>
  31       <segtitle>&diskspace;</segtitle>
  32
  33       <seglistitem>
  34         <seg>&systemd-fin-sbu;</seg>
  35         <seg>&systemd-fin-du;</seg>
  36       </seglistitem>
  37     </segmentedlist>
  38   </sect2>
  39
  40   <sect2 role="installation">
  41     <title>Installation of systemd</title>
  42
  43 <!--
  44     <para>First, apply a patch to fix the build with GCC-10 and fix a segfault:</para>
  45
  46 <screen><userinput remap="pre">patch -Np1 -i ../systemd-&systemd-version;-gcc_10-fixes-2.patch</userinput></screen>
  47 -->
  48
  49     <!-- For linux-5.11's API headers changing the rfkill_event structure -->
  50     <para>First, apply a patch to fix some regressions and fix functionality
  51     with future versions of the kernel:</para>
  52
  53 <screen><userinput remap="pre">patch -Np1 -i ../systemd-&systemd-version;-upstream_fixes-2.patch</userinput></screen>
  54
  55     <para>Remove tests that cannot be built in chroot:</para>
  56
  57 <screen><userinput remap="pre">sed '181,$ d' -i src/resolve/meson.build</userinput></screen>
  58
  59     <para>Remove an unneeded group,
  60     <systemitem class="groupname">render</systemitem>, from the default udev
  61     rules:</para>
  62
  63 <screen><userinput remap="pre">sed -i 's/GROUP="render"/GROUP="video"/' rules.d/50-udev-default.rules.in</userinput></screen>
  64
  65     <para>Prepare systemd for compilation:</para>
  66
  67 <screen><userinput remap="configure">mkdir -p build
  68 cd       build
  69
  70 LANG=en_US.UTF-8                    \
  71 meson --prefix=/usr                 \
  72       --sysconfdir=/etc             \
  73       --localstatedir=/var          \
  74       -Dblkid=true                  \
  75       -Dbuildtype=release           \
  76       -Ddefault-dnssec=no           \
  77       -Dfirstboot=false             \
  78       -Dinstall-tests=false         \
  79       -Dkmod-path=/bin/kmod         \
  80       -Dldconfig=false              \
  81       -Dmount-path=/bin/mount       \
  82       -Drootprefix=                 \
  83       -Drootlibdir=/lib             \
  84       -Dsplit-usr=true              \
  85       -Dsulogin-path=/sbin/sulogin  \
  86       -Dsysusers=false              \
  87       -Dumount-path=/bin/umount     \
  88       -Db_lto=false                 \
  89       -Drpmmacrosdir=no             \
  90       -Dhomed=false                 \
  91       -Duserdb=false                \
  92       -Dman=false                   \
  93       -Dmode=release                \
  94       -Ddocdir=/usr/share/doc/systemd-&systemd-version; \
  95       ..</userinput></screen>
  96
  97     <variablelist>
  98       <title>The meaning of the meson options:</title>
  99
 100       <varlistentry>
 101         <term><parameter>-D*-path=*</parameter></term>
 102         <listitem>
 103           <para>These switches provide the location of binaries needed by
 104           systemd at runtime that have not yet been installed.</para>
 105         </listitem>
 106       </varlistentry>
 107
 108       <varlistentry>
 109         <term><parameter>-Ddefault-dnssec=no</parameter></term>
 110         <listitem>
 111           <para>This switch turns off the experimental DNSSEC support.</para>
 112         </listitem>
 113       </varlistentry>
 114
 115       <varlistentry>
 116         <term><parameter>-Dfirstboot=false</parameter></term>
 117         <listitem>
 118           <para>This switch prevents installation of systemd
 119           services responsible for setting up the system for
 120           the first time. They are not useful for LFS because
 121           everything is done manually.</para>
 122         </listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term><parameter>-Dinstall-tests=false</parameter></term>
 127         <listitem>
 128           <para>This switch prevents installation of the compiled tests.</para>
 129         </listitem>
 130       </varlistentry>
 131
 132       <varlistentry>
 133         <term><parameter>-Dldconfig=false</parameter></term>
 134         <listitem>
 135           <para>This switch prevents installation of a systemd unit that runs
 136           <command>ldconfig</command> at boot, which is not useful for source
 137           distributions such as LFS and makes the boot time longer. Remove it
 138           if the described feature is desired.</para>
 139         </listitem>
 140       </varlistentry>
 141
 142       <varlistentry>
 143         <term><parameter>-Droot*</parameter></term>
 144         <listitem>
 145           <para>These switches ensure that core programs and
 146           shared libraries are installed in subdirectories
 147           of the root partition.</para>
 148         </listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><parameter>-Dsplit-usr=true</parameter></term>
 153         <listitem>
 154           <para>This switch ensures that systemd will work on
 155           systems where /bin, /lib and /sbin directories are not
 156           symlinks to their /usr counterparts.</para>
 157         </listitem>
 158       </varlistentry>
 159
 160       <varlistentry>
 161         <term><parameter>-Dsysusers=false</parameter></term>
 162         <listitem>
 163           <para>This switch prevents installation of systemd
 164           services responsible for setting up the
 165           <filename>/etc/group</filename> and
 166           <filename>/etc/passwd</filename> files. Both files
 167           were created earlier in this chapter.</para>
 168         </listitem>
 169       </varlistentry>
 170
 171       <varlistentry>
 172         <term><parameter>-Drpmmacrosdir=no</parameter></term>
 173         <listitem>
 174           <para>This switch disables installation of RPM Macros
 175           for use with systemd because LFS does not support RPM.</para>
 176         </listitem>
 177       </varlistentry>
 178
 179       <varlistentry>
 180         <term><parameter>-D{userdb,homed}=false</parameter></term>
 181         <listitem>
 182           <para>Remove two daemons that have dependencies that do not fit
 183           the scope of LFS.</para>
 184         </listitem>
 185       </varlistentry>
 186
 187       <varlistentry>
 188         <term><parameter>-Dman=false</parameter></term>
 189         <listitem>
 190           <para>Prevent the generation of man pages to avoid extra
 191           dependencies.  We will install pre-generated man pages for systemd
 192           from a tarball later.</para>
 193         </listitem>
 194       </varlistentry>
 195
 196       <varlistentry>
 197         <term><parameter>-Dmode=release</parameter></term>
 198         <listitem>
 199           <para>Disable some features considered experimental by upstream.
 200           </para>
 201         </listitem>
 202       </varlistentry>
 203
 204     </variablelist>
 205
 206     <para>Compile the package:</para>
 207
 208 <screen><userinput remap="make">LANG=en_US.UTF-8 ninja</userinput></screen>
 209
 210     <para>Install the package:</para>
 211
 212 <screen><userinput remap="install">LANG=en_US.UTF-8 ninja install</userinput></screen>
 213
 214     <para>Install the man pages:</para>
 215
 216 <screen><userinput remap="install">tar -xf ../../systemd-man-pages-&systemd-man-version;.tar.xz --strip-components=1 -C /usr/share/man</userinput></screen>
 217
 218     <para>Remove a useless directory:</para>
 219
 220 <screen><userinput remap="install">rm -rf /usr/lib/pam.d</userinput></screen>
 221
 222     <para>Create the <filename>/etc/machine-id</filename> file needed by
 223     <command>systemd-journald</command>:</para>
 224
 225 <screen><userinput remap="adjust">systemd-machine-id-setup</userinput></screen>
 226
 227     <para>Setup the basic target structure:</para>
 228
 229 <screen><userinput remap="adjust">systemctl preset-all</userinput></screen>
 230
 231     <para>Disable a service that is known to cause problems with systems that
 232     use a network configuration other than what is provided by
 233     systemd-networkd:</para>
 234     <!-- Observed halting startup with dhcpcd handling the primary NIC -->
 235
 236 <screen><userinput remap="adjust">systemctl disable systemd-time-wait-sync.service</userinput></screen>
 237
 238 <!-- dev: 50-pid-max.conf is not removed in BLFS, so I commented the following out.
 239           If it causes any trouble, we can add this back and also copy it into BLFS -->
 240 <!--
 241     <para>Prevent systemd from resetting the maximum PID value which causes
 242     some problems with packages and units in BLFS:</para>
 243
 244 <screen><userinput remap="adjust">rm -f /usr/lib/sysctl.d/50-pid-max.conf</userinput></screen>
 245 -->
 246
 247   </sect2>
 248
 249   <sect2 id="contents-systemd" role="content">
 250     <title>Contents of systemd</title>
 251
 252     <segmentedlist>
 253       <segtitle>Installed programs</segtitle>
 254       <segtitle>Installed libraries</segtitle>
 255       <segtitle>Installed directories</segtitle>
 256
 257       <seglistitem>
 258         <seg>bootctl, busctl, coredumpctl, halt (symlink to systemctl),
 259         hostnamectl, init, journalctl, kernel-install, localectl, loginctl,
 260         machinectl, networkctl, portablectl, poweroff (symlink to
 261         systemctl), reboot (symlink to systemctl), resolvconf (symlink to
 262         resolvectl), resolvectl, runlevel (symlink to systemctl), shutdown
 263         (symlink to systemctl), systemctl, systemd-analyze,
 264         systemd-ask-password, systemd-cat, systemd-cgls, systemd-cgtop,
 265         systemd-delta, systemd-detect-virt, systemd-dissect, systemd-escape,
 266         systemd-hwdb, systemd-id128, systemd-inhibit, systemd-machine-id-setup,
 267         systemd-mount, systemd-notify, systemd-nspawn, systemd-path,
 268         systemd-repart, systemd-resolve (symlink to resolvectl), systemd-run,
 269         systemd-socket-activate, systemd-stdio-bridge, systemd-tmpfiles,
 270         systemd-tty-ask-password-agent, systemd-umount (symlink to
 271         systemd-mount), telinit (symlink to systemctl), timedatectl, and
 272         udevadm</seg>
 273         <seg>libnss_myhostname.so.2, libnss_mymachines.so.2,
 274         libnss_resolve.so.2, libnss_systemd.so.2,
 275         libsystemd.so, libsystemd-shared-&systemd-version;.so (in /lib/systemd),
 276         and libudev.so</seg>
 277         <seg>/etc/binfmt.d, /etc/init.d, /etc/kernel, /etc/modules-load.d,
 278         /etc/sysctl.d, /etc/systemd, /etc/tmpfiles.d, /etc/udev,
 279         /etc/xdg/systemd, /lib/systemd, /lib/udev, /usr/include/systemd,
 280         /usr/lib/binfmt.d, /usr/lib/environment.d, /usr/lib/kernel,
 281         /usr/lib/modules-load.d, /usr/lib/sysctl.d, /usr/lib/systemd,
 282         /usr/lib/tmpfiles.d,
 283         /usr/share/doc/systemd-&systemd-version;, /usr/share/factory,
 284         /usr/share/systemd, /var/lib/systemd, and /var/log/journal</seg>
 285       </seglistitem>
 286     </segmentedlist>
 287
 288     <variablelist>
 289       <bridgehead renderas="sect3">Short Descriptions</bridgehead>
 290       <?dbfo list-presentation="list"?>
 291       <?dbhtml list-presentation="table"?>
 292
 293       <varlistentry id="bootctl">
 294         <term><command>bootctl</command></term>
 295         <listitem>
 296           <para>Is used to query the firmware and boot manager settings</para>
 297           <indexterm zone="ch-system-systemd bootctl">
 298             <primary sortas="b-bootctl">bootctl</primary>
 299           </indexterm>
 300         </listitem>
 301       </varlistentry>
 302
 303       <varlistentry id="busctl">
 304         <term><command>busctl</command></term>
 305         <listitem>
 306           <para>Is used to introspect and monitor the D-Bus bus</para>
 307           <indexterm zone="ch-system-systemd busctl">
 308             <primary sortas="b-busctl">busctl</primary>
 309           </indexterm>
 310         </listitem>
 311       </varlistentry>
 312
 313       <varlistentry id="coredumpctl">
 314         <term><command>coredumpctl</command></term>
 315         <listitem>
 316           <para>Is used to retrieve coredumps from the systemd journal</para>
 317           <indexterm zone="ch-system-systemd coredumpctl">
 318             <primary sortas="b-coredumpctl">coredumpctl</primary>
 319           </indexterm>
 320         </listitem>
 321       </varlistentry>
 322
 323       <varlistentry id="halt">
 324         <term><command>halt</command></term>
 325         <listitem>
 326           <para>Normally invokes <command>shutdown</command> with the
 327           <parameter>-h</parameter> option, except when already in run-level 0,
 328           then it tells the kernel to halt the system; it notes in the
 329           file <filename>/var/log/wtmp</filename> that the system is being
 330           brought down</para>
 331           <indexterm zone="ch-system-systemd halt">
 332             <primary sortas="b-halt">halt</primary>
 333           </indexterm>
 334         </listitem>
 335       </varlistentry>
 336
 337       <varlistentry id="hostnamectl">
 338         <term><command>hostnamectl</command></term>
 339         <listitem>
 340           <para>Is used to query and change the system hostname and related
 341           settings</para>
 342           <indexterm zone="ch-system-systemd hostnamectl">
 343             <primary sortas="b-hostnamectl">hostnamectl</primary>
 344           </indexterm>
 345         </listitem>
 346       </varlistentry>
 347
 348       <varlistentry id="init">
 349         <term><command>init</command></term>
 350         <listitem>
 351           <para>Is the first process to be started when the kernel has initialized
 352           the hardware which takes over the boot process and starts all
 353           processes according to its configuration files. In this case, it starts
 354           systemd</para>
 355           <indexterm zone="ch-system-systemd init">
 356             <primary sortas="b-init">init</primary>
 357           </indexterm>
 358         </listitem>
 359       </varlistentry>
 360
 361       <varlistentry id="journalctl">
 362         <term><command>journalctl</command></term>
 363         <listitem>
 364           <para>Is used to query the contents of the systemd journal</para>
 365           <indexterm zone="ch-system-systemd journalctl">
 366             <primary sortas="b-journalctl">journalctl</primary>
 367           </indexterm>
 368         </listitem>
 369       </varlistentry>
 370
 371       <varlistentry id="kernel-install">
 372         <term><command>kernel-install</command></term>
 373         <listitem>
 374           <para>Is used to add and remove kernel and initramfs images to and
 375           from /boot. In LFS, this is done manually</para>
 376           <indexterm zone="ch-system-systemd kernel-install">
 377             <primary sortas="b-kernel-install">kernel-install</primary>
 378           </indexterm>
 379         </listitem>
 380       </varlistentry>
 381
 382       <varlistentry id="localectl">
 383         <term><command>localectl</command></term>
 384         <listitem>
 385           <para>Is used to query and change the system locale and keyboard layout
 386           settings</para>
 387           <indexterm zone="ch-system-systemd localectl">
 388             <primary sortas="b-localectl">localectl</primary>
 389           </indexterm>
 390         </listitem>
 391       </varlistentry>
 392
 393       <varlistentry id="loginctl">
 394         <term><command>loginctl</command></term>
 395         <listitem>
 396           <para>Is used to introspect and control the state of the systemd Login
 397           Manager</para>
 398           <indexterm zone="ch-system-systemd loginctl">
 399             <primary sortas="b-loginctl">loginctl</primary>
 400           </indexterm>
 401         </listitem>
 402       </varlistentry>
 403
 404       <varlistentry id="machinectl">
 405         <term><command>machinectl</command></term>
 406         <listitem>
 407           <para>Is used to introspect and control the state of the systemd Virtual
 408           Machine and Container Registration Manager</para>
 409           <indexterm zone="ch-system-systemd machinectl">
 410             <primary sortas="b-machinectl">machinectl</primary>
 411           </indexterm>
 412         </listitem>
 413       </varlistentry>
 414
 415       <varlistentry id="networkctl">
 416         <term><command>networkctl</command></term>
 417         <listitem>
 418           <para>Is used to introspect and configure the state of the network
 419           links configured by systemd-networkd</para>
 420           <indexterm zone="ch-system-systemd networkctl">
 421             <primary sortas="b-networkctl">networkctl</primary>
 422           </indexterm>
 423         </listitem>
 424       </varlistentry>
 425
 426       <varlistentry id="portablectl">
 427         <term><command>portablectl</command></term>
 428         <listitem>
 429           <para>Is used to attach or detach portable services from the local
 430           system</para>
 431           <indexterm zone="ch-system-systemd portablectl">
 432             <primary sortas="b-portablectl">portablectl</primary>
 433           </indexterm>
 434         </listitem>
 435       </varlistentry>
 436
 437       <varlistentry id="poweroff">
 438         <term><command>poweroff</command></term>
 439         <listitem>
 440           <para>Instructs the kernel to halt the system and switch off the computer
 441           (see <command>halt</command>)</para>
 442           <indexterm zone="ch-system-systemd poweroff">
 443             <primary sortas="b-poweroff">poweroff</primary>
 444           </indexterm>
 445         </listitem>
 446       </varlistentry>
 447
 448       <varlistentry id="reboot">
 449         <term><command>reboot</command></term>
 450         <listitem>
 451           <para>Instructs the kernel to reboot the system (see
 452           <command>halt</command>)</para>
 453           <indexterm zone="ch-system-systemd reboot">
 454             <primary sortas="b-reboot">reboot</primary>
 455           </indexterm>
 456         </listitem>
 457       </varlistentry>
 458
 459       <varlistentry id="resolvconf">
 460         <term><command>resolvconf</command></term>
 461         <listitem>
 462           <para>Registers DNS server and domain configuration with
 463           <command>systemd-resolved</command></para>
 464           <indexterm zone="ch-system-systemd resolvconf">
 465             <primary sortas="b-resolvconf">resolvconf</primary>
 466           </indexterm>
 467         </listitem>
 468       </varlistentry>
 469
 470       <varlistentry id="resolvectl">
 471         <term><command>resolvectl</command></term>
 472         <listitem>
 473           <para>Sends control commands to the network name resolution
 474           manager, or resolves domain names, IPv4 and IPv6 addresses,
 475           DNS records, and services</para>
 476           <indexterm zone="ch-system-systemd resolvectl">
 477             <primary sortas="b-resolvectl">resolvectl</primary>
 478           </indexterm>
 479         </listitem>
 480       </varlistentry>
 481
 482       <varlistentry id="runlevel">
 483         <term><command>runlevel</command></term>
 484         <listitem>
 485           <para>Outputs the previous and the current run-level, as noted in the
 486           last run-level record in <filename>/run/utmp</filename></para>
 487           <indexterm zone="ch-system-systemd runlevel">
 488             <primary sortas="b-runlevel">runlevel</primary>
 489           </indexterm>
 490         </listitem>
 491       </varlistentry>
 492
 493       <varlistentry id="shutdown">
 494         <term><command>shutdown</command></term>
 495         <listitem>
 496           <para>Brings the system down in a safe and secure manner, signaling
 497           all processes and notifying all logged-in users</para>
 498           <indexterm zone="ch-system-systemd shutdown">
 499             <primary sortas="b-shutdown">shutdown</primary>
 500           </indexterm>
 501         </listitem>
 502       </varlistentry>
 503
 504       <varlistentry id="systemctl">
 505         <term><command>systemctl</command></term>
 506         <listitem>
 507           <para>Is used to introspect and control the state of the systemd system
 508           and service manager</para>
 509           <indexterm zone="ch-system-systemd systemctl">
 510             <primary sortas="b-systemctl">systemctl</primary>
 511           </indexterm>
 512         </listitem>
 513       </varlistentry>
 514
 515       <varlistentry id="systemd-analyze">
 516         <term><command>systemd-analyze</command></term>
 517         <listitem>
 518           <para>Is used to determine system startup performance of the current
 519           boot, as well as identify troublesome systemd units</para>
 520           <indexterm zone="ch-system-systemd systemd-analyze">
 521             <primary sortas="b-systemd-analyze">systemd-analyze</primary>
 522           </indexterm>
 523         </listitem>
 524       </varlistentry>
 525
 526       <varlistentry id="systemd-ask-password">
 527         <term><command>systemd-ask-password</command></term>
 528         <listitem>
 529           <para>Is used to query a system password or passphrase from the user,
 530           using a question message specified on the command line</para>
 531           <indexterm zone="ch-system-systemd systemd-ask-password">
 532             <primary sortas="b-systemd-ask-password">systemd-ask-password</primary>
 533           </indexterm>
 534         </listitem>
 535       </varlistentry>
 536
 537       <varlistentry id="systemd-cat">
 538         <term><command>systemd-cat</command></term>
 539         <listitem>
 540           <para>Is used to connect the STDOUT and STDERR outputs of a process
 541           with the systemd journal
 542           </para>
 543           <indexterm zone="ch-system-systemd systemd-cat">
 544             <primary sortas="b-systemd-cat">systemd-cat</primary>
 545           </indexterm>
 546         </listitem>
 547       </varlistentry>
 548
 549       <varlistentry id="systemd-cgls">
 550         <term><command>systemd-cgls</command></term>
 551         <listitem>
 552           <para>Recursively shows the contents of the selected Linux control
 553           group hierarchy in a tree</para>
 554           <indexterm zone="ch-system-systemd systemd-cgls">
 555             <primary sortas="b-systemd-cgls">systemd-cgls</primary>
 556           </indexterm>
 557         </listitem>
 558       </varlistentry>
 559
 560       <varlistentry id="systemd-cgtop">
 561         <term><command>systemd-cgtop</command></term>
 562         <listitem>
 563           <para>Shows the top control groups of the local Linux control group
 564           hierarchy, ordered by their CPU, memory and disk I/O load</para>
 565           <indexterm zone="ch-system-systemd systemd-cgtop">
 566             <primary sortas="b-systemd-cgtop">systemd-cgtop</primary>
 567           </indexterm>
 568         </listitem>
 569       </varlistentry>
 570
 571       <varlistentry id="systemd-delta">
 572         <term><command>systemd-delta</command></term>
 573         <listitem>
 574           <para>Is used to identify and compare configuration files in
 575           <filename class="directory">/etc</filename> that override default
 576           counterparts in <filename class="directory">/usr</filename></para>
 577           <indexterm zone="ch-system-systemd systemd-delta">
 578             <primary sortas="b-systemd-delta">systemd-delta</primary>
 579           </indexterm>
 580         </listitem>
 581       </varlistentry>
 582
 583       <varlistentry id="systemd-detect-virt">
 584         <term><command>systemd-detect-virt</command></term>
 585         <listitem>
 586           <para>Detects whether the system is being run in a virtual
 587           environment, and adjusts udev accordingly</para>
 588           <indexterm zone="ch-system-systemd systemd-detect-virt">
 589             <primary sortas="b-systemd-detect-virt">systemd-detect-virt</primary>
 590           </indexterm>
 591         </listitem>
 592       </varlistentry>
 593
 594       <varlistentry id="systemd-dissect">
 595         <term><command>systemd-dissect</command></term>
 596         <listitem>
 597           <para>Is used to inspect OS disk images</para>
 598           <indexterm zone="ch-system-systemd systemd-dissect">
 599             <primary sortas="b-systemd-dissect">systemd-dissect</primary>
 600           </indexterm>
 601         </listitem>
 602       </varlistentry>
 603
 604       <varlistentry id="systemd-escape">
 605         <term><command>systemd-escape</command></term>
 606         <listitem>
 607           <para>Is used to escape strings for inclusion in systemd unit
 608           names</para>
 609           <indexterm zone="ch-system-systemd systemd-escape">
 610             <primary sortas="b-systemd-escape">systemd-escape</primary>
 611           </indexterm>
 612         </listitem>
 613       </varlistentry>
 614
 615       <varlistentry id="systemd-hwdb">
 616         <term><command>systemd-hwdb</command></term>
 617         <listitem>
 618           <para>Is used to manage the hardware database (hwdb)</para>
 619           <indexterm zone="ch-system-systemd systemd-hwdb">
 620             <primary sortas="b-systemd-hwdb">systemd-hwdb</primary>
 621           </indexterm>
 622         </listitem>
 623       </varlistentry>
 624
 625       <varlistentry id="systemd-id128">
 626         <term><command>systemd-id128</command></term>
 627         <listitem>
 628           <para>Generates and prints id128 strings</para>
 629           <indexterm zone="ch-system-systemd systemd-id128">
 630             <primary sortas="b-systemd-id128">systemd-id128</primary>
 631           </indexterm>
 632         </listitem>
 633       </varlistentry>
 634
 635       <varlistentry id="systemd-inhibit">
 636         <term><command>systemd-inhibit</command></term>
 637         <listitem>
 638           <para>Is used to execute a program with a shutdown, sleep or idle
 639           inhibitor lock taken, preventing an action such as a system shutdown
 640           until the process is completed</para>
 641           <indexterm zone="ch-system-systemd systemd-inhibit">
 642             <primary sortas="b-systemd-inhibit">systemd-inhibit</primary>
 643           </indexterm>
 644         </listitem>
 645       </varlistentry>
 646
 647       <varlistentry id="systemd-machine-id-setup">
 648         <term><command>systemd-machine-id-setup</command></term>
 649         <listitem>
 650           <para>Is used by system installer tools to initialize the machine ID
 651           stored in <filename>/etc/machine-id</filename> at install time with a
 652           randomly generated ID</para>
 653           <indexterm zone="ch-system-systemd systemd-machine-id-setup">
 654             <primary sortas="b-systemd-machine-id-setup">systemd-machine-id-setup</primary>
 655           </indexterm>
 656         </listitem>
 657       </varlistentry>
 658
 659       <varlistentry id="systemd-mount">
 660         <term><command>systemd-mount</command></term>
 661         <listitem>
 662           <para>Is used to temporarily mount or automount disks</para>
 663           <indexterm zone="ch-system-systemd systemd-mount">
 664             <primary sortas="b-systemd-mount">systemd-mount</primary>
 665           </indexterm>
 666         </listitem>
 667       </varlistentry>
 668
 669       <varlistentry id="systemd-notify">
 670         <term><command>systemd-notify</command></term>
 671         <listitem>
 672           <para>Is used by daemon scripts to notify the init system about status
 673           changes</para>
 674           <indexterm zone="ch-system-systemd systemd-notify">
 675             <primary sortas="b-systemd-notify">systemd-notify</primary>
 676           </indexterm>
 677         </listitem>
 678       </varlistentry>
 679
 680       <varlistentry id="systemd-nspawn">
 681         <term><command>systemd-nspawn</command></term>
 682         <listitem>
 683           <para>Is used to run a command or OS in a light-weight namespace
 684           container</para>
 685           <indexterm zone="ch-system-systemd systemd-nspawn">
 686             <primary sortas="b-systemd-nspawn">systemd-nspawn</primary>
 687           </indexterm>
 688         </listitem>
 689       </varlistentry>
 690
 691       <varlistentry id="systemd-path">
 692         <term><command>systemd-path</command></term>
 693         <listitem>
 694           <para>Is used to query system and user paths</para>
 695           <indexterm zone="ch-system-systemd systemd-path">
 696             <primary sortas="b-systemd-path">systemd-path</primary>
 697           </indexterm>
 698         </listitem>
 699       </varlistentry>
 700
 701       <varlistentry id="systemd-repart">
 702         <term><command>systemd-repart</command></term>
 703         <listitem>
 704           <para>Is used to grow and add partitions to a partition table when
 705           systemd is used in an OS image (e.g. a container)</para>
 706           <indexterm zone="ch-system-systemd systemd-repart">
 707             <primary sortas="b-systemd-repart">systemd-repart</primary>
 708           </indexterm>
 709         </listitem>
 710       </varlistentry>
 711
 712       <varlistentry id="systemd-resolve">
 713         <term><command>systemd-resolve</command></term>
 714         <listitem>
 715           <para>Is used to resolve domain names, IPV4 and IPv6 addresses, DNS
 716           resource records, and services</para>
 717           <indexterm zone="ch-system-systemd systemd-resolve">
 718             <primary sortas="b-systemd-resolve">systemd-resolve</primary>
 719           </indexterm>
 720         </listitem>
 721       </varlistentry>
 722
 723       <varlistentry id="systemd-run">
 724         <term><command>systemd-run</command></term>
 725         <listitem>
 726           <para>Is used to create and start a transient .service or a .scope
 727           unit and run the specified command in it. This is useful for
 728           validating systemd units</para>
 729           <indexterm zone="ch-system-systemd systemd-run">
 730             <primary sortas="b-systemd-run">systemd-run</primary>
 731           </indexterm>
 732         </listitem>
 733       </varlistentry>
 734
 735       <varlistentry id="systemd-socket-activate">
 736         <term><command>systemd-socket-activate</command></term>
 737         <listitem>
 738           <para>Is used to listen on socket devices and launch a process upon
 739           a successful connection to the socket</para>
 740           <indexterm zone="ch-system-systemd systemd-socket-activate">
 741             <primary sortas="b-systemd-socket-activate">systemd-socket-activate</primary>
 742           </indexterm>
 743         </listitem>
 744       </varlistentry>
 745
 746       <varlistentry id="systemd-tmpfiles">
 747         <term><command>systemd-tmpfiles</command></term>
 748         <listitem>
 749           <para>Creates, deletes and cleans up volatile and temporary files and
 750           directories, based on the configuration file format and location
 751           specified in
 752           <filename class="directory">tmpfiles.d</filename> directories</para>
 753           <indexterm zone="ch-system-systemd systemd-tmpfiles">
 754             <primary sortas="b-systemd-tmpfiles">systemd-tmpfiles</primary>
 755           </indexterm>
 756         </listitem>
 757       </varlistentry>
 758
 759       <varlistentry id="systemd-umount">
 760         <term><command>systemd-umount</command></term>
 761         <listitem>
 762           <para>Unmounts mount points</para>
 763           <indexterm zone="ch-system-systemd systemd-umount">
 764             <primary sortas="b-systemd-umount">systemd-umount</primary>
 765           </indexterm>
 766         </listitem>
 767       </varlistentry>
 768
 769       <varlistentry id="systemd-tty-ask-password-agent">
 770         <term><command>systemd-tty-ask-password-agent</command></term>
 771         <listitem>
 772           <para>Is used to list and/or process pending systemd password
 773           requests</para>
 774           <indexterm zone="ch-system-systemd systemd-tty-ask-password-agent">
 775             <primary sortas="b-systemd-tty-ask-password-agent">systemd-tty-ask-password-agent</primary>
 776           </indexterm>
 777         </listitem>
 778       </varlistentry>
 779
 780       <varlistentry id="telinit">
 781         <term><command>telinit</command></term>
 782         <listitem>
 783           <para>Tells <command>init</command> which run-level to change
 784           to</para>
 785           <indexterm zone="ch-system-systemd telinit">
 786             <primary sortas="b-telinit">telinit</primary>
 787           </indexterm>
 788         </listitem>
 789       </varlistentry>
 790
 791       <varlistentry id="timedatectl">
 792         <term><command>timedatectl</command></term>
 793         <listitem>
 794           <para>Is used to query and change the system clock and its settings
 795           </para>
 796           <indexterm zone="ch-system-systemd timedatectl">
 797             <primary sortas="b-timedatectl">timedatectl</primary>
 798           </indexterm>
 799         </listitem>
 800       </varlistentry>
 801
 802       <varlistentry id="udevadm">
 803         <term><command>udevadm</command></term>
 804         <listitem>
 805           <para>Is a generic udev administration tool which controls the udevd
 806           daemon, provides info from the Udev hardware database, monitors
 807           uevents, waits for uevents to finish, tests udev configuration, and
 808           triggers uevents for a given device</para>
 809           <indexterm zone="ch-system-systemd udevadm">
 810             <primary sortas="b-udevadm">udevadm</primary>
 811           </indexterm>
 812         </listitem>
 813       </varlistentry>
 814
 815       <varlistentry id="libsystemd">
 816         <term><filename class="libraryfile">libsystemd</filename></term>
 817         <listitem>
 818           <para>Is the main systemd utility library</para>
 819           <indexterm zone="ch-system-systemd libsystemd">
 820             <primary sortas="c-libsystemd">libsystemd</primary>
 821           </indexterm>
 822         </listitem>
 823       </varlistentry>
 824
 825       <varlistentry id="libudev">
 826         <term><filename class="libraryfile">libudev</filename></term>
 827         <listitem>
 828           <para>Is a library to access Udev device information</para>
 829           <indexterm zone="ch-system-systemd libudev">
 830             <primary sortas="c-libudev">libudev</primary>
 831           </indexterm>
 832         </listitem>
 833       </varlistentry>
 834
 835     </variablelist>
 836
 837   </sect2>
 838
 839 </sect1>