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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../general.ent">
%general-entities;
]>
<sect1 id="ch-scripts-systemd-custom">
<?dbhtml filename="systemd-custom.html"?>
<title>Systemd Usage and Configuration</title>
<indexterm zone="ch-scripts-systemd-custom">
<primary sortas="e-Systemd">Systemd Customization</primary>
</indexterm>
<sect2>
<title>Basic Configuration</title>
<para>The <filename>/etc/systemd/system.conf</filename> file contains a set
of options to control basic systemd operations. The default file has all
entries commented out with the default settings indicated. This file is
where the log level may be changed as well as some basic logging settings.
See <filename>systemd-system.conf(5)</filename> manual page for details on
each configuration option.</para>
</sect2>
<sect2>
<title>Disabling Screen Clearing at Boot Time</title>
<para>The normal behavior for systemd is to clear the screen at
the end of the boot sequence. If desired, this behavior may be
changed by running the following command:</para>
<screen role="nodump"><userinput>mkdir -pv /etc/systemd/system/getty@tty1.service.d
cat > /etc/systemd/system/getty@tty1.service.d/noclear.conf << EOF
<literal>[Service]
TTYVTDisallocate=no</literal>
EOF</userinput></screen>
<para>The boot messages can always be revied by using the
<userinput>journalctl -b</userinput> command as the root user.</para>
</sect2>
<sect2>
<title>Disabling tmpfs for /tmp</title>
<para>By default, <filename class="directory">/tmp</filename> is created as
a tmpfs. If this is not desired, it can be overridden by the following:</para>
<screen role="nodump"><userinput>ln -sfv /dev/null /etc/systemd/system/tmp.mount</userinput></screen>
<para>This is not necessary if there is a separate partition for
<filename class="directory">/tmp</filename> specified in
<filename>/etc/fstab</filename>.</para>
</sect2>
<sect2>
<title>Configuring Automatic File Creation and Deletion</title>
<para>There are several services that create or delete files or
directories:</para>
<itemizedlist>
<listitem><para>systemd-tmpfiles-clean.service</para></listitem>
<listitem><para>systemd-tmpfiles-setup-dev.service</para></listitem>
<listitem><para>systemd-tmpfiles-setup.service</para></listitem>
</itemizedlist>
<para>The system location for the configuration files is
<filename>/usr/lib/tmpfiles.d/*.conf</filename>. The local
configuration files are in
<filename class="directory">/etc/tmpfiles.d</filename>. Files in
<filename class="directory">/etc/tmpfiles.d</filename> override
files with the same name in
<filename class="directory">/usr/lib/tmpfiles.d</filename>. See
<filename>tmpfiles.d(5)</filename> manual page for file format
details.</para>
</sect2>
<sect2>
<title>Overriding Default Services Behavior</title>
<para>A systemd service contents can be overriden by creating a directory
and a configuration file in <filename
class="directory">/etc/systemd/system</filename>. For example:</para>
<screen role="nodump"><userinput>mkdir -pv /etc/systemd/system/foobar.service.d
cat > /etc/systemd/system/foobar.service.d/foobar.conf << EOF
<literal>[Service]
Restart=always
RestartSec=30</literal>
EOF</userinput></screen>
<para>See <filename>systemd.unit(5)</filename> manual page for more
information. After creating the configuration file, run
<userinput>systemctl daemon-reload</userinput> and <userinput>systemctl
restart foobar</userinput> to activate the changes to a service.</para>
</sect2>
<sect2>
<title>Debugging the Boot Sequence</title>
<para>There are several commands that can be used to help debug the systemd
boot process. Here are some examples:</para>
<itemizedlist>
<listitem><para>systemctl list-units -t service [--all]</para></listitem>
<listitem><para>systemctl list-units -t target [--all]</para></listitem>
<listitem><para>systemctl show -p Wants multi-user.target</para></listitem>
<listitem><para>systemctl status sshd.service</para></listitem>
</itemizedlist>
</sect2>
<!--TBA
<sect2>
<title>Working with journalctl</title>
<para>Logging on a system booted with systemd is handled by the systemd
journal.</para>
<itemizedlist>
<listitem><para>journalctl -r </para></listitem>
<listitem><para>journalctl -u <replaceable>UNIT</replaceable></para></listitem>
<listitem><para>journalctl -b[=ID] -r</para></listitem>
<listitem><para>journalctl -f</para></listitem>
</itemizedlist>
</sect2>
-->
</sect1>
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