man/sysusers.d.xml

   1 <?xml version="1.0"?>
   2 <!--*-nxml-*-->
   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!--
   5   This file is part of systemd.
   6
   7   Copyright 2014 Lennart Poettering
   8
   9   systemd is free software; you can redistribute it and/or modify it
  10   under the terms of the GNU Lesser General Public License as published by
  11   the Free Software Foundation; either version 2.1 of the License, or
  12   (at your option) any later version.
  13
  14   systemd is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   Lesser General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public License
  20   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  21 -->
  22 <refentry id="sysusers.d"
  23           xmlns:xi="http://www.w3.org/2001/XInclude">
  24
  25         <refentryinfo>
  26                 <title>sysusers.d</title>
  27                 <productname>systemd</productname>
  28
  29                 <authorgroup>
  30                         <author>
  31                                 <contrib>Developer</contrib>
  32                                 <firstname>Lennart</firstname>
  33                                 <surname>Poettering</surname>
  34                                 <email>lennart@poettering.net</email>
  35                         </author>
  36                 </authorgroup>
  37         </refentryinfo>
  38
  39         <refmeta>
  40                 <refentrytitle>sysusers.d</refentrytitle>
  41                 <manvolnum>5</manvolnum>
  42         </refmeta>
  43
  44         <refnamediv>
  45                 <refname>sysusers.d</refname>
  46                 <refpurpose>Declarative allocation of system users and groups</refpurpose>
  47         </refnamediv>
  48
  49         <refsynopsisdiv>
  50                 <para><filename>/usr/lib/sysusers.d/*.conf</filename></para>
  51         </refsynopsisdiv>
  52
  53         <refsect1>
  54                 <title>Description</title>
  55
  56                 <para><command>systemd-sysusers</command> uses the
  57                 files from <filename>sysusers.d</filename> directory
  58                 to create system users and groups at package
  59                 installation or boot time. This tool may be used to
  60                 allocate system users and groups only, it is not
  61                 useful for creating non-system users and groups, as it
  62                 accesses <filename>/etc/passwd</filename> and
  63                 <filename>/etc/group</filename> directly, bypassing
  64                 any more complex user databases, for example any
  65                 database involving NIS or LDAP.</para>
  66         </refsect1>
  67
  68         <refsect1>
  69                 <title>Configuration Format</title>
  70
  71                 <para>Each configuration file shall be named in the
  72                 style of
  73                 <filename><replaceable>package</replaceable>.conf</filename>
  74                 or
  75                 <filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>.
  76                 The second variant should be used when it is desirable
  77                 to make it easy to override just this part of
  78                 configuration.</para>
  79
  80                 <para>The file format is one line per user or group
  81                 containing name, ID, GECOS field description and home directory:</para>
  82
  83                 <programlisting># Type Name ID GECOS
  84 u httpd 440 "HTTP User"
  85 u authd /usr/bin/authd "Authorization user"
  86 g input - -
  87 m authd input
  88 u root 0 "Superuser" /root</programlisting>
  89
  90                 <refsect2>
  91                         <title>Type</title>
  92
  93                         <para>The type consists of a single
  94                         letter. The following line types are
  95                         understood:</para>
  96
  97                         <variablelist>
  98                                 <varlistentry>
  99                                         <term><varname>u</varname></term>
 100                                         <listitem><para>Create a
 101                                         system user and group of the
 102                                         specified name should they not
 103                                         exist yet. The user's primary
 104                                         group will be set to the group
 105                                         bearing the same name. The
 106                                         user's shell will be set to
 107                                         <filename>/sbin/nologin</filename>,
 108                                         the home directory to the
 109                                         specified home directory, or
 110                                         <filename>/</filename> if none
 111                                         is given. The account will be
 112                                         created disabled, so that
 113                                         logins are not
 114                                         allowed.</para></listitem>
 115                                 </varlistentry>
 116
 117                                 <varlistentry>
 118                                         <term><varname>g</varname></term>
 119                                         <listitem><para>Create a
 120                                         system group of the specified
 121                                         name should it not exist
 122                                         yet. Note that
 123                                         <varname>u</varname>
 124                                         implicitly create a matching
 125                                         group. The group will be
 126                                         created with no password
 127                                         set.</para></listitem>
 128                                 </varlistentry>
 129
 130                                 <varlistentry>
 131                                         <term><varname>m</varname></term>
 132                                         <listitem><para>Add a user to
 133                                         a group. If the user or group
 134                                         are not existing yet, they
 135                                         will be implicitly
 136                                         created.</para></listitem>
 137                                 </varlistentry>
 138
 139                                 <varlistentry>
 140                                         <term><varname>r</varname></term>
 141                                         <listitem><para>Add a range of
 142                                         numeric UIDs/GIDs to the pool
 143                                         to allocate new UIDs and GIDs
 144                                         from. If no line of this type
 145                                         is specified the range of
 146                                         UIDs/GIDs is set to some
 147                                         compiled-in default. Note that
 148                                         both UIDs and GIDs are
 149                                         allocated from the same pool,
 150                                         in order to ensure that users
 151                                         and groups of the same name
 152                                         are likely to carry the same
 153                                         numeric UID and
 154                                         GID.</para></listitem>
 155                                 </varlistentry>
 156
 157                         </variablelist>
 158                 </refsect2>
 159
 160                 <refsect2>
 161                         <title>Name</title>
 162
 163                         <para>The name field specifies the user or
 164                         group name. It should be shorter than 31
 165                         characters and avoid any non-ASCII characters,
 166                         and not begin with a numeric character. It is
 167                         strongly recommended to pick user and group
 168                         names that are unlikely to clash with normal
 169                         users created by the administrator. A good
 170                         scheme to guarantee this is by prefixing all
 171                         system and group names with the underscore,
 172                         and avoiding too generic names.</para>
 173
 174                         <para>For <varname>m</varname> lines this
 175                         field should contain the user name to add to a
 176                         group.</para>
 177
 178                         <para>For lines of type <varname>r</varname>
 179                         this field should be set to
 180                         <literal>-</literal>.</para>
 181                 </refsect2>
 182
 183                 <refsect2>
 184                         <title>ID</title>
 185
 186                         <para>For <varname>u</varname> and
 187                         <varname>g</varname> the numeric 32bit UID or
 188                         GID of the user/group. Do not use IDs 65535 or
 189                         4294967295, as they have special placeholder
 190                         meanings. Specify <literal>-</literal> for
 191                         automatic UID/GID allocation for the user or
 192                         group. Alternatively, specify an absolute path
 193                         in the file system. In this case the UID/GID
 194                         is read from the path's owner/group. This is
 195                         useful to create users whose UID/GID match the
 196                         owners of pre-existing files (such as SUID or
 197                         SGID binaries).</para>
 198
 199                         <para>For <varname>m</varname> lines this
 200                         field should contain the group name to add to
 201                         a user to.</para>
 202
 203                         <para>For lines of type <varname>r</varname>
 204                         this field should be set to a UID/GID range in
 205                         the format <literal>FROM-TO</literal> where
 206                         both values are formatted as decimal ASCII
 207                         numbers. Alternatively, a single UID/GID may
 208                         be specified formatted as decimal ASCII
 209                         numbers.</para>
 210                 </refsect2>
 211
 212                 <refsect2>
 213                         <title>GECOS</title>
 214
 215                         <para>A short, descriptive string for users to
 216                         be created, enclosed in quotation marks. Note
 217                         that this field may not contain colons.</para>
 218
 219                         <para>Only applies to lines of type
 220                         <varname>u</varname> and should otherwise be
 221                         left unset, or be set to
 222                         <literal>-</literal>.</para>
 223                 </refsect2>
 224
 225                 <refsect2>
 226                         <title>Home Directory</title>
 227
 228                         <para>The home directory for a new system
 229                         user. If omitted defaults to the root
 230                         directory. It is recommended to not
 231                         unnecessarily specify home directories for
 232                         system users, unless software strictly
 233                         requires one to be set.</para>
 234
 235                         <para>Only applies to lines of type
 236                         <varname>u</varname> and should otherwise be
 237                         left unset, or be set to
 238                         <literal>-</literal>.</para>
 239                 </refsect2>
 240
 241         </refsect1>
 242
 243         <xi:include href="standard-conf.xml" xpointer="confd" />
 244
 245         <refsect1>
 246                 <title>Idempotence</title>
 247
 248                 <para>Note that <command>systemd-sysusers</command>
 249                 will do nothing if the specified users or groups
 250                 already exist, so normally there no reason to override
 251                 <filename>sysusers.d</filename> vendor configuration,
 252                 except to block certain users or groups from being
 253                 created.</para>
 254         </refsect1>
 255
 256         <refsect1>
 257                 <title>See Also</title>
 258                 <para>
 259                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 260                         <citerefentry><refentrytitle>systemd-sysusers</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 261                 </para>
 262         </refsect1>
 263
 264 </refentry>