<?xml version="1.0"?>

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="sysusers.d">

<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>

</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>

</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>

</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>

<refsect1>

<title>Overriding vendor configuration</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>

<para>Files in <filename>/etc/sysusers.d</filename>

override files with the same name in

<filename>/usr/lib/sysusers.d</filename> and

<filename>/run/sysusers.d</filename>. Files in

<filename>/run/sysusers.d</filename> override files

with the same name in

<filename>/usr/lib/sysusers.d</filename>. The scheme is the same as for

<citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

except for the directory name.</para>

<para>If the administrator wants to disable a

configuration file supplied by the vendor, the

recommended way is to place a symlink to

<filename>/dev/null</filename> in

<filename>/etc/sysusers.d/</filename> bearing the

same filename.</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>,

<citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>