source: BOOK/bootscripts/common/usage.xml@ 8000b26

clfs-3.0.0-systemd clfs-3.0.0-sysvinit systemd sysvinit
Last change on this file since 8000b26 was 774f0a37, checked in by William Harrington <kb0iic@…>, 11 years ago

Add some detailed information regarding systemd usage. It could use some polishing.

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File size: 5.0 KB
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[3f8be484]1<?xml version="1.0" encoding="ISO-8859-1"?>
[aa18ac0]2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
[3f8be484]4 <!ENTITY % general-entities SYSTEM "../../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="ch-scripts-usage">
9 <?dbhtml filename="usage.html"?>
10
[24213983]11 <title>How does Systemd work?</title>
[3f8be484]12
13 <indexterm zone="ch-scripts-usage">
[24213983]14 <primary sortas="a-systemd-usage">Systemd usage</primary>
[3f8be484]15 <secondary>usage</secondary></indexterm>
16
[6cc3c3f]17 <warning>
[774f0a37]18 <para>Please disregard this page until it is complete and verified.</para>
[6cc3c3f]19 </warning>
[774f0a37]20
21 <sect2>
22 <title>Introduction to Systemd</title>
23
24
25 <para>Systemd is a system management daemon designed exclusively for the
26 Linux kernel API. In the Linux startup process, it is the first process to
27 execute in user land; therefore, it is also the parent process of all child
28 processes in user land.</para>
29
30 <para>Systemd's initialization instructions for each daemon are recorded in
31 a declarative configuration file rather than a shell script. For
32 inter-process communication, systemd makes Unix domain sockets and D-Bus
33 available to the running daemons. Because systemd tracks processes using
34 Linux cgroups instead of process identifiers (PIDs), daemons cannot "escape"
35 systemd; not even by double-forking. Systemd is also capable of aggressive
36 parallelization.</para>
37
38 <para>Among systemd's auxiliary features are a cron-like job scheduler
39 called systemd Calendar Timers, and an event logging subsystem called
40 journal. The system administrator may choose whether to log system events
41 with systemd or syslog. Systemd's logfile is a binary file. The state of
42 systemd itself can be preserved in a snapshot for future recall.</para>
43
44 <para>Systemd provides a replacement for sysvinit, pm-utils, inetd, acpid,
45 syslog, watchdog, cron and atd, and obsoletes ConsoleKit.</para>
46
47 </sect2>
48
49 <sect2>
50 <title>Systemctl</title>
51
52 <para><command>systemctl</command> is the main command used to introspect
53 and control Systemd.</para>
54
55 <variablelist>
56
57 <varlistentry>
58 <term>List running units:</term>
59 <listitem>
60 <para><command>systemctl</command> or <command>systemctl list-units</command></para>
61 </listitem>
62 </varlistentry>
63
64 <varlistentry>
65 <term>List failed units:</term>
66 <listitem>
67 <para><command>systemctl --failed</command></para>
68 </listitem>
69 </varlistentry>
70
71 <varlistentry>
72 <term>List avilable unit files:</term>
73 <listitem>
74 <para><command>systemctl list-unit-files</command></para>
75 </listitem>
76 </varlistentry>
77
78 <varlistentry>
79 <term>Activate a unit immediately:</term>
80 <listitem>
81 <para><command>systemctl start</command> <replaceable>unit</replaceable></para>
82 </listitem>
83 </varlistentry>
84
85 <varlistentry>
86 <term>Stop a unit immediately:</term>
87 <listitem>
88 <para><command>systemctl stop </command><replaceable>unit</replaceable></para>
89 </listitem>
90 </varlistentry>
91
92 <varlistentry>
93 <term>Restart a unit:</term>
94 <listitem>
95 <para><command>systemctl restart </command><replaceable>unit</replaceable></para>
96 </listitem>
97 </varlistentry>
98
99 <varlistentry>
100 <term>Reload unit configuration:</term>
101 <listitem>
102 <para><command>systemctl reload </command><replaceable>unit</replaceable></para>
103 </listitem>
104 </varlistentry>
105
106 <varlistentry>
107 <term>Show status of a unit:</term>
108 <listitem>
109 <para><command>systemctl status </command><replaceable>unit</replaceable></para>
110 </listitem>
111 </varlistentry>
112
113 <varlistentry>
114 <term>Check if a unit is enabled or disabled:</term>
115 <listitem>
116 <para><command>systemctl is-enabled </command><replaceable>unit</replaceable></para>
117 </listitem>
118 </varlistentry>
119
120 <varlistentry>
121 <term>Enable a unit to start during boot:</term>
122 <listitem>
123 <para><command>systemctl enable </command><replaceable>unit</replaceable></para>
124 </listitem>
125 </varlistentry>
126
127 <varlistentry>
128 <term>Disable a unit to not start during boot:</term>
129 <listitem>
130 <para><command>systemctl disable </command><replaceable>unit</replaceable></para>
131 </listitem>
132 </varlistentry>
133
134 <varlistentry>
135 <term>Reload systemd and scan for new or changed units:</term>
136 <listitem>
137 <para><command>systemctl daemon-reload</command></para>
138 </listitem>
139 </varlistentry>
140
141 </variablelist>
142
143 <para>For more information regarding systemd, please refer to the systemd
144 and related man-pages and
145 <ulink url="https://fedoraproject.org/wiki/Systemd">Systemd at
146 FedoraProject</ulink> for documentation, examples, features, and other
147 information.</para>
148
149 </sect2>
[3f8be484]150
151</sect1>
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