Systemd/man/systemd-sysusers.xml
Zbigniew Jędrzejewski-Szmek d16a1c1bb6 sysusers: allow admin/runtime overrides to command-line config
When used in a package installation script, we want to invoke systemd-sysusers
before that package is installed (so it can contain files owned by the newly
created user), so the configuration to use is specified on the command
line. This should be a copy of the configuration that will be installed as
/usr/lib/sysusers.d/package.conf. We still want to obey any overrides in
/etc/sysusers.d or /run/sysusers.d in the usual fashion. Otherwise, we'd get a
different result when systemd-sysusers is run with a copy of the new config on
the command line and when systemd-sysusers is run at boot after package
instalation. In the second case any files in /etc or /run have higher priority,
so the same should happen when the configuration is given on the command line.
More generally, we want the behaviour in this special case to be as close to
the case where the file is finally on disk as possible, so we have to read all
configuration files, since they all might contain overrides and additional
configuration that matters. Even files that have lower priority might specify
additional groups for the user we are creating. Thus, we need to read all
configuration, but insert our new configuration somewhere with the right
priority.

If --target=/path/to/file.conf is given on the command line, we gather the list
of files, and pretend that the command-line config is read from
/path/to/file.conf (doesn't matter if the file on disk actually exists or
not). All package scripts should use this option to obtain consistent and
idempotent behaviour.

The corner case when --target= is specified and there are no positional
arguments is disallowed.

v1:
- version with --config-name=
v2:
- disallow --config-name= and no positional args
v3:
- remove --config-name=
v4:
- add --target= and rework the code completely
v5:
- fix argcounting bug and add example in man page
v6:
- rename --target to --replace
2018-02-02 10:40:22 +01:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!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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This file is part of systemd.
Copyright 2014 Lennart Poettering
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You should have received a copy of the GNU Lesser General Public License
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-->
<refentry id="systemd-sysusers"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-sysusers</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-sysusers</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-sysusers</refname>
<refname>systemd-sysusers.service</refname>
<refpurpose>Allocate system users and groups</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-sysusers</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="opt" rep="repeat"><replaceable>CONFIGFILE</replaceable></arg>
</cmdsynopsis>
<para><filename>systemd-sysusers.service</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-sysusers</command> creates system users and
groups, based on the file format and location specified in
<citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>If invoked with no arguments, it applies all directives from all files
found in the directories specified by
<citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
When invoked with positional arguments, if option
<option>--replace=<replaceable>PATH</replaceable></option> is specified, arguments
specified on the command line are used instead of the configuration file
<replaceable>PATH</replaceable>. Otherwise, just the configuration specified by
the command line arguments is executed. The string <literal>-</literal> may be
specified instead of a filename to instruct <command>systemd-sysusers</command>
to read the configuration from standard input. If only the basename of a file is
specified, all configuration directories are searched for a matching file and
the file found that has the highest priority is executed.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--root=<replaceable>root</replaceable></option></term>
<listitem><para>Takes a directory path as an argument. All
paths will be prefixed with the given alternate
<replaceable>root</replaceable> path, including config search
paths. </para></listitem>
</varlistentry>
<varlistentry>
<term><option>--replace=<replaceable>PATH</replaceable></option></term>
<listitem><para>When this option is given, one ore more positional arguments
must be specified. All configuration files found in the directories listed in
<citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
will be read, and the configuration given on the command line will be
handled instead of and with the same priority as the configuration file
<replaceable>PATH</replaceable>.</para>
<para>This option is intended to be used when package installation scripts
are running and files belonging to that package are not yet available on
disk, so their contents must be given on the command line, but the admin
configuration might already exist and should be given higher priority.
</para>
<example>
<title>RPM installation script for radvd</title>
<programlisting>echo 'u radvd - "radvd daemon"' | \
systemd-sysusers --replace=/usr/lib/sysusers.d/radvd.conf -</programlisting>
<para>This will create the radvd user as if
<filename>/usr/lib/sysusers.d/radvd.conf</filename> was already on disk.
An admin might override the configuration specified on the command line by
placing <filename>/etc/sysusers.d/radvd.conf</filename> or even
<filename>/etc/sysusers.d/00-overrides.conf</filename>.</para>
<para>Note that this is the expanded from, and when used in a package, this
would be written using a macro with "radvd" and a file containing the
configuration line as arguments.</para>
</example>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--inline</option></term>
<listitem><para>Treat each positional argument as a separate configuration
line instead of a file name.</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure code
otherwise.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>