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1d84ad9445
This improves kernel command line parsing in a number of ways: a) An kernel option "foo_bar=xyz" is now considered equivalent to "foo-bar-xyz", i.e. when comparing kernel command line option names "-" and "_" are now considered equivalent (this only applies to the option names though, not the option values!). Most of our kernel options used "-" as word separator in kernel command line options so far, but some used "_". With this change, which was a source of confusion for users (well, at least of one user: myself, I just couldn't remember that it's systemd.debug-shell, not systemd.debug_shell). Considering both as equivalent is inspired how modern kernel module loading normalizes all kernel module names to use underscores now too. b) All options previously using a dash for separating words in kernel command line options now use an underscore instead, in all documentation and in code. Since a) has been implemented this should not create any compatibility problems, but normalizes our documentation and our code. c) All kernel command line options which take booleans (or are boolean-like) have been reworked so that "foobar" (without argument) is now equivalent to "foobar=1" (but not "foobar=0"), thus normalizing the handling of our boolean arguments. Specifically this means systemd.debug-shell and systemd_debug_shell=1 are now entirely equivalent. d) All kernel command line options which take an argument, and where no argument is specified will now result in a log message. e.g. passing just "systemd.unit" will no result in a complain that it needs an argument. This is implemented in the proc_cmdline_missing_value() function. e) There's now a call proc_cmdline_get_bool() similar to proc_cmdline_get_key() that parses booleans (following the logic explained in c). f) The proc_cmdline_parse() call's boolean argument has been replaced by a new flags argument that takes a common set of bits with proc_cmdline_get_key(). g) All kernel command line APIs now begin with the same "proc_cmdline_" prefix. h) There are now tests for much of this. Yay!
96 lines
3.6 KiB
XML
96 lines
3.6 KiB
XML
<?xml version="1.0"?>
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<!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-debug-generator">
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<refentryinfo>
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<title>systemd-debug-generator</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-debug-generator</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-debug-generator</refname>
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<refpurpose>Generator for enabling a runtime debug shell and
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masking specific units at boot</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/usr/lib/systemd/system-generators/systemd-debug-generator</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-debug-generator</filename> is a generator
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that reads the kernel command line and understands three
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options:</para>
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<para>If the <option>systemd.mask=</option> option is specified
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and followed by a unit name, this unit is masked for the runtime,
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similar to the effect of
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>mask</command> command. This is useful to boot with
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certain units removed from the initial boot transaction for
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debugging system startup. May be specified more than once.</para>
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<para>If the <option>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
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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.</para>
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<para>If the <option>systemd.debug_shell</option> option is
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specified, the debug shell service
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<literal>debug-shell.service</literal> is pulled into the boot
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transaction. It will spawn a debug shell on tty9 during early
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system startup. Note that the shell may also be turned on
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persistently by enabling it with
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>enable</command> command.</para>
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<para><filename>systemd-debug-generator</filename> implements
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<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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