man/systemd-debug-generator.xml

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   8 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   9 <refentry id="systemd-debug-generator">
  10
  11   <refentryinfo>
  12     <title>systemd-debug-generator</title>
  13     <productname>systemd</productname>
  14   </refentryinfo>
  15
  16   <refmeta>
  17     <refentrytitle>systemd-debug-generator</refentrytitle>
  18     <manvolnum>8</manvolnum>
  19   </refmeta>
  20
  21   <refnamediv>
  22     <refname>systemd-debug-generator</refname>
  23     <refpurpose>Generator for enabling a runtime debug shell and
  24     masking specific units at boot</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <para><filename>/usr/lib/systemd/system-generators/systemd-debug-generator</filename></para>
  29   </refsynopsisdiv>
  30
  31   <refsect1>
  32     <title>Description</title>
  33
  34     <para><filename>systemd-debug-generator</filename> is a generator
  35     that reads the kernel command line and understands three
  36     options:</para>
  37
  38     <para>If the <option>systemd.mask=</option> or <option>rd.systemd.mask=</option>
  39     option is specified and followed by a unit name, this unit is
  40     masked for the runtime, similar to the effect of
  41     <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  42     <command>mask</command> command. This is useful to boot with
  43     certain units removed from the initial boot transaction for
  44     debugging system startup. May be specified more than once.
  45     <option>rd.systemd.mask=</option> is honored only by initial
  46     RAM disk (initrd) while <option>systemd.mask=</option> is
  47     honored only in the main system.</para>
  48
  49     <para>If the <option>systemd.wants=</option> or
  50     <option>rd.systemd.wants=</option> option is specified
  51     and followed by a unit name, a start job for this unit is added to
  52     the initial transaction. This is useful to start one or more
  53     additional units at boot. May be specified more than once.
  54     <option>rd.systemd.wants=</option> is honored only by initial
  55     RAM disk (initrd) while <option>systemd.wants=</option> is
  56     honored only in the main system.</para>
  57
  58     <para>If the <option>systemd.debug_shell</option> or
  59     <option>rd.systemd.debug_shell</option> option is
  60     specified, the debug shell service
  61     <literal>debug-shell.service</literal> is pulled into the boot
  62     transaction and a debug shell will be spawned during early boot.
  63     By default, <filename>&DEBUGTTY;</filename> is used, but a specific tty can also be set,
  64     either with or without the <filename>/dev/</filename> prefix.
  65     Note that the shell may also be turned on persistently by enabling it with
  66     <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  67     <command>enable</command> command.
  68     <option>rd.systemd.debug_shell=</option> is honored only by initial
  69     RAM disk (initrd) while <option>systemd.debug_shell</option> is
  70     honored only in the main system.</para>
  71
  72     <para><filename>systemd-debug-generator</filename> implements
  73     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  74   </refsect1>
  75
  76   <refsect1>
  77     <title>See Also</title>
  78     <para>
  79       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  80       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  81       <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  82     </para>
  83   </refsect1>
  84
  85 </refentry>