man/systemd-debug-generator.xml

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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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   5 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   6 <refentry id="systemd-debug-generator">
   7
   8   <refentryinfo>
   9     <title>systemd-debug-generator</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>systemd-debug-generator</refentrytitle>
  15     <manvolnum>8</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>systemd-debug-generator</refname>
  20     <refpurpose>Generator for enabling a runtime debug shell and
  21     masking specific units at boot</refpurpose>
  22   </refnamediv>
  23
  24   <refsynopsisdiv>
  25     <para><filename>/usr/lib/systemd/system-generators/systemd-debug-generator</filename></para>
  26   </refsynopsisdiv>
  27
  28   <refsect1>
  29     <title>Description</title>
  30
  31     <para><filename>systemd-debug-generator</filename> is a generator
  32     that reads the kernel command line and understands three
  33     options:</para>
  34
  35     <para>If the <option>systemd.mask=</option> or <option>rd.systemd.mask=</option>
  36     option is specified and followed by a unit name, this unit is
  37     masked for the runtime, similar to the effect of
  38     <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  39     <command>mask</command> command. This is useful to boot with
  40     certain units removed from the initial boot transaction for
  41     debugging system startup. May be specified more than once.
  42     <option>rd.systemd.mask=</option> is honored only by initial
  43     RAM disk (initrd) while <option>systemd.mask=</option> is
  44     honored only in the main system.</para>
  45
  46     <para>If the <option>systemd.wants=</option> or
  47     <option>rd.systemd.wants=</option> option is specified
  48     and followed by a unit name, a start job for this unit is added to
  49     the initial transaction. This is useful to start one or more
  50     additional units at boot. May be specified more than once.
  51     <option>rd.systemd.wants=</option> is honored only by initial
  52     RAM disk (initrd) while <option>systemd.wants=</option> is
  53     honored only in the main system.</para>
  54
  55     <para>If the <option>systemd.debug_shell</option> or
  56     <option>rd.systemd.debug_shell</option> option is
  57     specified, the debug shell service
  58     <literal>debug-shell.service</literal> is pulled into the boot
  59     transaction. It will spawn a debug shell on tty9 during early
  60     system startup. Note that the shell may also be turned on
  61     persistently by enabling it with
  62     <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  63     <command>enable</command> command.
  64     <option>rd.systemd.debug_shell=</option> is honored only by initial
  65     RAM disk (initrd) while <option>systemd.debug_shell</option> is
  66     honored only in the main system.</para>
  67
  68     <para><filename>systemd-debug-generator</filename> implements
  69     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  70   </refsect1>
  71
  72   <refsect1>
  73     <title>See Also</title>
  74     <para>
  75       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  76       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  77       <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  78     </para>
  79   </refsect1>
  80
  81 </refentry>