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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">
<!--
This file is part of systemd.
Copyright 2014 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sysusers.d" conditional='ENABLE_SYSUSERS'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sysusers.d</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>sysusers.d</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>sysusers.d</refname>
<refpurpose>Declarative allocation of system users and groups</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/usr/lib/sysusers.d/*.conf</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-sysusers</command> uses the files from
<filename>sysusers.d</filename> directory to create system users
and groups at package installation or boot time. This tool may be
used to allocate system users and groups only, it is not useful
for creating non-system users and groups, as it accesses
<filename>/etc/passwd</filename> and
<filename>/etc/group</filename> directly, bypassing any more
complex user databases, for example any database involving NIS or
LDAP.</para>
</refsect1>
<refsect1>
<title>Configuration Format</title>
<para>Each configuration file shall be named in the style of
<filename><replaceable>package</replaceable>.conf</filename> or
<filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>.
The second variant should be used when it is desirable to make it
easy to override just this part of configuration.</para>
<para>The file format is one line per user or group containing
name, ID, GECOS field description and home directory:</para>
<programlisting># Type Name ID GECOS
u httpd 440 "HTTP User"
u authd /usr/bin/authd "Authorization user"
g input - -
m authd input
u root 0 "Superuser" /root</programlisting>
<refsect2>
<title>Type</title>
<para>The type consists of a single letter. The following line
types are understood:</para>
<variablelist>
<varlistentry>
<term><varname>u</varname></term>
<listitem><para>Create a system user and group of the
specified name should they not exist yet. The user's primary
group will be set to the group bearing the same name. The
user's shell will be set to
<filename>/sbin/nologin</filename>, the home directory to
the specified home directory, or <filename>/</filename> if
none is given. The account will be created disabled, so that
logins are not allowed.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>g</varname></term>
<listitem><para>Create a system group of the specified name
should it not exist yet. Note that <varname>u</varname>
implicitly create a matching group. The group will be
created with no password set.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>m</varname></term>
<listitem><para>Add a user to a group. If the user or group
are not existing yet, they will be implicitly
created.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>r</varname></term>
<listitem><para>Add a range of numeric UIDs/GIDs to the pool
to allocate new UIDs and GIDs from. If no line of this type
is specified the range of UIDs/GIDs is set to some
compiled-in default. Note that both UIDs and GIDs are
allocated from the same pool, in order to ensure that users
and groups of the same name are likely to carry the same
numeric UID and GID.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2>
<title>Name</title>
<para>The name field specifies the user or group name. It should
be shorter than 31 characters and avoid any non-ASCII
characters, and not begin with a numeric character. It is
strongly recommended to pick user and group names that are
unlikely to clash with normal users created by the
administrator. A good scheme to guarantee this is by prefixing
all system and group names with the underscore, and avoiding too
generic names.</para>
<para>For <varname>m</varname> lines this field should contain
the user name to add to a group.</para>
<para>For lines of type <varname>r</varname> this field should
be set to <literal>-</literal>.</para>
</refsect2>
<refsect2>
<title>ID</title>
<para>For <varname>u</varname> and <varname>g</varname> the
numeric 32bit UID or GID of the user/group. Do not use IDs 65535
or 4294967295, as they have special placeholder meanings.
Specify <literal>-</literal> for automatic UID/GID allocation
for the user or group. Alternatively, specify an absolute path
in the file system. In this case the UID/GID is read from the
path's owner/group. This is useful to create users whose UID/GID
match the owners of pre-existing files (such as SUID or SGID
binaries).</para>
<para>For <varname>m</varname> lines this field should contain
the group name to add to a user to.</para>
<para>For lines of type <varname>r</varname> this field should
be set to a UID/GID range in the format
<literal>FROM-TO</literal> where both values are formatted as
decimal ASCII numbers. Alternatively, a single UID/GID may be
specified formatted as decimal ASCII numbers.</para>
</refsect2>
<refsect2>
<title>GECOS</title>
<para>A short, descriptive string for users to be created,
enclosed in quotation marks. Note that this field may not
contain colons.</para>
<para>Only applies to lines of type <varname>u</varname> and
should otherwise be left unset, or be set to
<literal>-</literal>.</para>
</refsect2>
<refsect2>
<title>Home Directory</title>
<para>The home directory for a new system user. If omitted
defaults to the root directory. It is recommended to not
unnecessarily specify home directories for system users, unless
software strictly requires one to be set.</para>
<para>Only applies to lines of type <varname>u</varname> and
should otherwise be left unset, or be set to
<literal>-</literal>.</para>
</refsect2>
</refsect1>
<xi:include href="standard-conf.xml" xpointer="confd" />
<refsect1>
<title>Idempotence</title>
<para>Note that <command>systemd-sysusers</command> will do
nothing if the specified users or groups already exist, so
normally there no reason to override
<filename>sysusers.d</filename> vendor configuration, except to
block certain users or groups from being created.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-sysusers</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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