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<!-- SPDX - License - Identifier: LGPL - 2.1 - or - later -->
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<refentry id= "systemd-debug-generator" xmlns:xi= "http://www.w3.org/2001/XInclude" >
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<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 >
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<para > <filename > /usr/lib/systemd/system-generators/systemd-debug-generator</filename> </para>
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</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>
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<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
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masked for the runtime (i.e. for this session — from boot to shutdown), similarly to the effect of
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<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
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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>
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<para > If the <option > systemd.wants=</option> or
<option > rd.systemd.wants=</option> option is specified
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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
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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>
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<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 specified, either with or without
the <filename > /dev/</filename> prefix. To set the tty to use without enabling the debug shell, the
<option > systemd.default_debug_tty=</option> option can be used which also takes a tty 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
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<command > enable</command> command. <option > rd.systemd.debug_shell</option> is honored only by initial
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RAM disk (initrd) while <option > systemd.debug_shell</option> is honored only in the main system.</para>
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<para > <filename > systemd-debug-generator</filename> implements
<citerefentry > <refentrytitle > systemd.generator</refentrytitle> <manvolnum > 7</manvolnum> </citerefentry> .</para>
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</refsect1>
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<refsect1 >
<title > System Credentials</title>
<variablelist class= 'system-credentials' >
<varlistentry >
<term > <varname > systemd.extra-unit.*</varname> </term>
<listitem > <para > Credentials prefixed with <literal > systemd.extra-unit.</literal> specify additional
units to add to the final system. Note that these additional units are added to both the initrd and
the final system. <varname > ConditionPathExists=!/etc/initrd-release</varname> can be used to make
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sure the unit is conditioned out in the initrd. Note that this can also be used to mask units, by
simply specifying an empty value.</para>
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<xi:include href= "version-info.xml" xpointer= "v256" /> </listitem>
</varlistentry>
<varlistentry >
<term > <varname > systemd.unit-dropin.*</varname> </term>
<listitem > <para > Credentials prefixed with <literal > systemd.unit-dropin.</literal> add drop-ins for
the corresponding units in the final system. Each credential must be suffixed with the full unit name
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including the unit extension. Its contents must be a valid unit drop-in file. Optionally, the unit
name may be followed with <literal > ~</literal> , followed by the drop-in name without the
<literal > .conf</literal> suffix. If not specified, the name of the generated drop-in will be
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<literal > 50-credential.conf</literal> . Note that these additional drop-ins are added to both the
initrd and the final system.</para>
<xi:include href= "version-info.xml" xpointer= "v256" /> </listitem>
</varlistentry>
</variablelist>
</refsect1>
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<refsect1 >
<title > See Also</title>
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<para > <simplelist type= "inline" >
<member > <citerefentry > <refentrytitle > systemd</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> </member>
<member > <citerefentry > <refentrytitle > systemctl</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> </member>
<member > <citerefentry > <refentrytitle > kernel-command-line</refentrytitle> <manvolnum > 7</manvolnum> </citerefentry> </member>
</simplelist> </para>
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</refsect1>
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</refentry>