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+ SPDX-License-Identifier: LGPL-2.1+
+
This file is part of systemd.
Copyright 2014 Lennart Poettering
<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 (i.e. regular, "human") 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>
+ <para><command>systemd-sysusers</command> uses the files from
+ <filename>sysusers.d</filename> directory to create system users and groups and
+ to add users to 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 (i.e. regular, "human") 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>
+ <title>Configuration Directories and Precedence</title>
<para>Each configuration file shall be named in the style of
<filename><replaceable>package</replaceable>.conf</filename> or
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>
+ <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>. Packages should
+ install their configuration files in
+ <filename>/usr/lib/sysusers.d</filename>. Files in
+ <filename>/etc/sysusers.d</filename> are reserved for the local
+ administrator, who may use this logic to override the
+ configuration files installed by vendor packages. All
+ configuration files are sorted by their filename in lexicographic
+ order, regardless of which of the directories they reside in. If
+ multiple files specify the same path, the entry in the file with
+ the lexicographically earliest name will be applied. All later
+ entries for the same user and group names will be logged as warnings.
+ </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>Configuration File Format</title>
- <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>
+ <para>The file format is one line per user or group containing name, ID, GECOS
+ field description, home directory, and login shell:</para>
+
+ <programlisting>#Type Name ID GECOS Home directory Shell
+u httpd 404 "HTTP User"
+u authd /usr/bin/authd "Authorization user"
+u postgres - "Postgresql Database" /var/lib/pgsql /usr/libexec/postgresdb
+g input - -
+m authd input
+u root 0 "Superuser" /root /bin/zsh</programlisting>
<para>Empty lines and lines beginning with the <literal>#</literal> character are ignored, and may be used for
commenting.</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>
+ <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 account will be created disabled, so that logins
+ are not allowed.</para></listitem>
</varlistentry>
<varlistentry>
numeric 32-bit 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
+ for the user or group (this is strongly recommended unless it is strictly
+ necessary to use a specific UID or GID). 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>
+ binaries).
+ The syntax <literal><replaceable>uid</replaceable>:<replaceable>gid</replaceable></literal> is also supported to
+ allow creating user and group pairs with different numeric UID and GID values. The group with the indicated GID must get created explicitly before or it must already exist. Specifying <literal>-</literal> for the UID in this syntax
+ is also supported.
+ </para>
<para>For <varname>m</varname> lines, this field should contain
the group name to add to a user to.</para>
<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>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>
+ <para>Only applies to lines of type <varname>u</varname> and should otherwise
+ be left unset (or <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>The home directory for a new system user. If omitted, defaults to the
+ root directory.</para>
- <para>Only applies to lines of type <varname>u</varname> and
- should otherwise be left unset, or be set to
- <literal>-</literal>.</para>
+ <para>Only applies to lines of type <varname>u</varname> and should otherwise
+ be left unset (or <literal>-</literal>). It is recommended to omit this, unless
+ software strictly requires a home directory to be set.</para>
</refsect2>
- </refsect1>
+ <refsect2>
+ <title>Shell</title>
- <xi:include href="standard-conf.xml" xpointer="confd" />
+ <para>The login shell of the user. If not specified, this will be set to
+ <filename>/sbin/nologin</filename>, except if the UID of the user is 0, in
+ which case <filename>/bin/sh</filename> will be used.</para>
+
+ <para>Only applies to lines of type <varname>u</varname> and should otherwise
+ be left unset (or <literal>-</literal>). It is recommended to omit this, unless
+ a shell different <filename>/sbin/nologin</filename> must be used.</para>
+ </refsect2>
+ </refsect1>
<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 is no reason to override
- <filename>sysusers.d</filename> vendor configuration, except to
- block certain users or groups from being created.</para>
+ <para>Note that <command>systemd-sysusers</command> will do nothing if the
+ specified users or groups already exist or the users are members of specified
+ groups, so normally there is no reason to override
+ <filename>sysusers.d</filename> vendor configuration, except to block certain
+ users or groups from being created.</para>
</refsect1>
<refsect1>
projects / thirdparty / systemd.git / blobdiff