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authorMichael Biebl <biebl@debian.org>2018-12-21 22:06:22 +0100
committerMichael Biebl <biebl@debian.org>2018-12-21 22:06:22 +0100
commit6e866b331d7cd4a5e0759dd160dea6edabd3678e (patch)
tree4d24c1ffe4ae946f04d8910956090e8d13aecd9a /man/systemd.xml
parentb012e92123bdc9fa10c2f079ec5bd9313b23e21a (diff)
downloadsystemd-6e866b331d7cd4a5e0759dd160dea6edabd3678e.tar.gz
New upstream version 240
Diffstat (limited to 'man/systemd.xml')
-rw-r--r--man/systemd.xml49
1 files changed, 35 insertions, 14 deletions
diff --git a/man/systemd.xml b/man/systemd.xml
index 17ab59beb5..49a29f9651 100644
--- a/man/systemd.xml
+++ b/man/systemd.xml
@@ -1,4 +1,4 @@
-<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
@@ -392,6 +392,25 @@
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details about these target units.</para>
+ <para>systemd only keeps a minimal set of units loaded into memory. Specifically, the only units that are kept
+ loaded into memory are those for which at least one of the following conditions is true:</para>
+
+ <orderedlist>
+ <listitem><para>It is in an active, activating, deactivating or failed state (i.e. in any unit state except for <literal>dead</literal>)</para></listitem>
+ <listitem><para>It has a job queued for it</para></listitem>
+ <listitem><para>It is a dependency of some sort of at least one other unit that is loaded into memory</para></listitem>
+ <listitem><para>It has some form of resource still allocated (e.g. a service unit that is inactive but for which
+ a process is still lingering that ignored the request to be terminated)</para></listitem>
+ <listitem><para>It has been pinned into memory programmatically by a D-Bus call</para></listitem>
+ </orderedlist>
+
+ <para>systemd will automatically and implicitly load units from disk — if they are not loaded yet — as soon as
+ operations are requested for them. Thus, in many respects, the fact whether a unit is loaded or not is invisible to
+ clients. Use <command>systemctl list-units --all</command> to comprehensively list all units currently loaded. Any
+ unit for which none of the conditions above applies is promptly unloaded. Note that when a unit is unloaded from
+ memory its accounting data is flushed out too. However, this data is generally not lost, as a journal log record
+ is generated declaring the consumed resources whenever a unit shuts down.</para>
+
<para>Processes systemd spawns are placed in individual Linux
control groups named after the unit which they belong to in the
private systemd hierarchy. (see <ulink
@@ -561,16 +580,15 @@
<varlistentry>
<term><constant>SIGINT</constant></term>
- <listitem><para>Upon receiving this signal the systemd system
- manager will start the
- <filename>ctrl-alt-del.target</filename> unit. This is mostly
- equivalent to <command>systemctl start ctrl-alt-del.target
- --job-mode=replace-irreversible</command>. If this signal is
- received more than 7 times per 2s, an immediate reboot is
- triggered. Note that pressing Ctrl-Alt-Del on the console
- will trigger this signal. Hence, if a reboot is hanging,
- pressing Ctrl-Alt-Del more than 7 times in 2s is a relatively
- safe way to trigger an immediate reboot.</para>
+ <listitem><para>Upon receiving this signal the systemd system manager will start the
+ <filename>ctrl-alt-del.target</filename> unit. This is mostly equivalent to
+ <command>systemctl start ctrl-alt-del.target --job-mode=replace-irreversible</command>. If
+ this signal is received more than 7 times per 2s, an immediate reboot is triggered. Note
+ that pressing
+ <keycombo><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Del</keycap></keycombo> on the
+ console will trigger this signal. Hence, if a reboot is hanging, pressing
+ <keycombo><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Del</keycap></keycombo> more than
+ 7 times in 2 seconds is a relatively safe way to trigger an immediate reboot.</para>
<para>systemd user managers treat this signal the same way as
<constant>SIGTERM</constant>.</para></listitem>
@@ -882,6 +900,9 @@
for more information.</para></listitem>
</varlistentry>
</variablelist>
+
+ <para>For further environment variables understood by systemd and its various components, see <ulink
+ url="https://systemd.io/ENVIRONMENT">Known Environment Variables</ulink>.</para>
</refsect1>
<refsect1>
@@ -1051,7 +1072,7 @@
hybrid or full legacy cgroup hierarchy.</para>
<para>If this option is not specified, the default behaviour is determined
- during compilation (the <option>--with-default-hierarchy=</option>
+ during compilation (the <option>-Ddefault-hierarchy=</option> meson
option). If the kernel does not support unified cgroup hierarchy, the legacy
hierarchy will be used even if this option is specified.</para>
</listitem>
@@ -1070,7 +1091,7 @@
the use of "hybrid" hierarchy.</para>
<para>If this option is not specified, the default behaviour is determined
- during compilation (the <option>--with-default-hierarchy=</option>
+ during compilation (the <option>-Ddefault-hierarchy=</option> meson
option). If the kernel does not support unified cgroup hierarchy, the legacy
hierarchy will be used even if this option is specified.</para>
</listitem>
@@ -1080,7 +1101,7 @@
<term><varname>quiet</varname></term>
<listitem><para>Turn off status output at boot, much like
- <varname>systemd.show_status=false</varname> would. Note that
+ <varname>systemd.show_status=no</varname> would. Note that
this option is also read by the kernel itself and disables
kernel log output. Passing this option hence turns off the
usual output from both the system manager and the kernel.