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<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-debug-generator">
<refentryinfo>
<title>systemd-debug-generator</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-debug-generator</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-debug-generator</refname>
<refpurpose>Generator for enabling a runtime debug shell and
masking specific units at boot</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/usr/lib/systemd/system-generators/systemd-debug-generator</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-debug-generator</filename> is a generator
that reads the kernel command line and understands three
options:</para>
<para>If the <option>systemd.mask=</option> or <option>rd.systemd.mask=</option>
option is specified and followed by a unit name, this unit is
masked for the runtime (i.e. for this session — from boot to shutdown), similarly to the effect of
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>mask</command> command. This is useful to boot with
certain units removed from the initial boot transaction for
debugging system startup. May be specified more than once.
<option>rd.systemd.mask=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.mask=</option> is
honored only in the main system.</para>
<para>If the <option>systemd.wants=</option> or
<option>rd.systemd.wants=</option> option is specified
and followed by a unit name, a start job for this unit is added to
the initial transaction. This is useful to start one or more
additional units at boot. May be specified more than once.
<option>rd.systemd.wants=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.wants=</option> is
honored only in the main system.</para>
<para>If the <option>systemd.debug_shell</option> or
<option>rd.systemd.debug_shell</option> option is
specified, the debug shell service
<literal>debug-shell.service</literal> is pulled into the boot
transaction and a debug shell will be spawned during early boot.
By default, <filename>&DEBUGTTY;</filename> is used, but a specific tty can also be set,
either with or without the <filename>/dev/</filename> prefix.
Note that the shell may also be turned on persistently by enabling it with
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>enable</command> command.
<option>rd.systemd.debug_shell=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.debug_shell</option> is
honored only in the main system.</para>
<para><filename>systemd-debug-generator</filename> implements
<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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