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1 | <?xml version="1.0"?> |
2 | <!--*-nxml-*--> | |
12b42c76 | 3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
21236ab5 | 4 | <!-- |
572eb058 | 5 | SPDX-License-Identifier: LGPL-2.1+ |
21236ab5 | 6 | --> |
e6de49ab | 7 | <refentry id="sysusers.d" conditional='ENABLE_SYSUSERS' |
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8 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
9 | ||
10 | <refentryinfo> | |
11 | <title>sysusers.d</title> | |
12 | <productname>systemd</productname> | |
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13 | </refentryinfo> |
14 | ||
15 | <refmeta> | |
16 | <refentrytitle>sysusers.d</refentrytitle> | |
17 | <manvolnum>5</manvolnum> | |
18 | </refmeta> | |
19 | ||
20 | <refnamediv> | |
21 | <refname>sysusers.d</refname> | |
22 | <refpurpose>Declarative allocation of system users and groups</refpurpose> | |
23 | </refnamediv> | |
24 | ||
25 | <refsynopsisdiv> | |
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26 | <para><filename>/etc/sysusers.d/*.conf</filename></para> |
27 | <para><filename>/run/sysusers.d/*.conf</filename></para> | |
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28 | <para><filename>/usr/lib/sysusers.d/*.conf</filename></para> |
29 | </refsynopsisdiv> | |
30 | ||
31 | <refsect1> | |
32 | <title>Description</title> | |
33 | ||
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34 | <para><command>systemd-sysusers</command> uses the files from |
35 | <filename>sysusers.d</filename> directory to create system users and groups and | |
36 | to add users to groups, at package installation or boot time. This tool may be | |
37 | used to allocate system users and groups only, it is not useful for creating | |
38 | non-system (i.e. regular, "human") users and groups, as it accesses | |
39 | <filename>/etc/passwd</filename> and <filename>/etc/group</filename> directly, | |
40 | bypassing any more complex user databases, for example any database involving NIS | |
41 | or LDAP.</para> | |
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42 | </refsect1> |
43 | ||
44 | <refsect1> | |
8165be2e | 45 | <title>Configuration Directories and Precedence</title> |
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46 | |
47 | <para>Each configuration file shall be named in the style of | |
48 | <filename><replaceable>package</replaceable>.conf</filename> or | |
49 | <filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>. | |
50 | The second variant should be used when it is desirable to make it | |
51 | easy to override just this part of configuration.</para> | |
52 | ||
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53 | <para>Files in <filename>/etc/sysusers.d</filename> override files |
54 | with the same name in <filename>/usr/lib/sysusers.d</filename> and | |
55 | <filename>/run/sysusers.d</filename>. Files in | |
56 | <filename>/run/sysusers.d</filename> override files with the same | |
57 | name in <filename>/usr/lib/sysusers.d</filename>. Packages should | |
58 | install their configuration files in | |
59 | <filename>/usr/lib/sysusers.d</filename>. Files in | |
60 | <filename>/etc/sysusers.d</filename> are reserved for the local | |
61 | administrator, who may use this logic to override the | |
62 | configuration files installed by vendor packages. All | |
63 | configuration files are sorted by their filename in lexicographic | |
64 | order, regardless of which of the directories they reside in. If | |
65 | multiple files specify the same path, the entry in the file with | |
66 | the lexicographically earliest name will be applied. All later | |
67 | entries for the same user and group names will be logged as warnings. | |
68 | </para> | |
69 | ||
70 | <para>If the administrator wants to disable a configuration file | |
71 | supplied by the vendor, the recommended way is to place a symlink | |
72 | to <filename>/dev/null</filename> in | |
73 | <filename>/etc/sysusers.d/</filename> bearing the same filename. | |
74 | </para> | |
75 | </refsect1> | |
76 | ||
77 | <refsect1> | |
78 | <title>Configuration File Format</title> | |
79 | ||
7b1aaf66 ZJS |
80 | <para>The file format is one line per user or group containing name, ID, GECOS |
81 | field description, home directory, and login shell:</para> | |
798d3a52 | 82 | |
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83 | <programlisting>#Type Name ID GECOS Home directory Shell |
84 | u httpd 404 "HTTP User" | |
85 | u authd /usr/bin/authd "Authorization user" | |
86 | u postgres - "Postgresql Database" /var/lib/pgsql /usr/libexec/postgresdb | |
87 | g input - - | |
88 | m authd input | |
89 | u root 0 "Superuser" /root /bin/zsh</programlisting> | |
21236ab5 | 90 | |
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91 | <para>Empty lines and lines beginning with the <literal>#</literal> character are ignored, and may be used for |
92 | commenting.</para> | |
93 | ||
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94 | <refsect2> |
95 | <title>Type</title> | |
96 | ||
97 | <para>The type consists of a single letter. The following line | |
98 | types are understood:</para> | |
99 | ||
100 | <variablelist> | |
101 | <varlistentry> | |
102 | <term><varname>u</varname></term> | |
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103 | <listitem><para>Create a system user and group of the specified name should |
104 | they not exist yet. The user's primary group will be set to the group | |
105 | bearing the same name. The account will be created disabled, so that logins | |
106 | are not allowed.</para></listitem> | |
798d3a52 ZJS |
107 | </varlistentry> |
108 | ||
109 | <varlistentry> | |
110 | <term><varname>g</varname></term> | |
111 | <listitem><para>Create a system group of the specified name | |
112 | should it not exist yet. Note that <varname>u</varname> | |
113 | implicitly create a matching group. The group will be | |
114 | created with no password set.</para></listitem> | |
115 | </varlistentry> | |
116 | ||
117 | <varlistentry> | |
118 | <term><varname>m</varname></term> | |
119 | <listitem><para>Add a user to a group. If the user or group | |
cd72d204 | 120 | do not exist yet, they will be implicitly |
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121 | created.</para></listitem> |
122 | </varlistentry> | |
123 | ||
124 | <varlistentry> | |
125 | <term><varname>r</varname></term> | |
126 | <listitem><para>Add a range of numeric UIDs/GIDs to the pool | |
127 | to allocate new UIDs and GIDs from. If no line of this type | |
b938cb90 | 128 | is specified, the range of UIDs/GIDs is set to some |
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129 | compiled-in default. Note that both UIDs and GIDs are |
130 | allocated from the same pool, in order to ensure that users | |
131 | and groups of the same name are likely to carry the same | |
132 | numeric UID and GID.</para></listitem> | |
133 | </varlistentry> | |
134 | ||
135 | </variablelist> | |
136 | </refsect2> | |
137 | ||
138 | <refsect2> | |
139 | <title>Name</title> | |
140 | ||
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141 | <para>The name field specifies the user or group name. The specified name must consist only of the characters a-z, |
142 | A-Z, 0-9, <literal>_</literal> and <literal>-</literal>, except for the first character which must be one of a-z, | |
143 | A-Z or <literal>_</literal> (i.e. numbers and <literal>-</literal> are not permitted as first character). The | |
144 | user/group name must have at least one character, and at most 31.</para> | |
145 | ||
146 | <para>It is strongly recommended to pick user and group names that are unlikely to clash with normal users | |
147 | created by the administrator. A good scheme to guarantee this is by prefixing all system and group names with the | |
148 | underscore, and avoiding too generic names.</para> | |
798d3a52 | 149 | |
b938cb90 | 150 | <para>For <varname>m</varname> lines, this field should contain |
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151 | the user name to add to a group.</para> |
152 | ||
b938cb90 | 153 | <para>For lines of type <varname>r</varname>, this field should |
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154 | be set to <literal>-</literal>.</para> |
155 | </refsect2> | |
156 | ||
157 | <refsect2> | |
158 | <title>ID</title> | |
159 | ||
b938cb90 JE |
160 | <para>For <varname>u</varname> and <varname>g</varname>, the |
161 | numeric 32-bit UID or GID of the user/group. Do not use IDs 65535 | |
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162 | or 4294967295, as they have special placeholder meanings. |
163 | Specify <literal>-</literal> for automatic UID/GID allocation | |
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164 | for the user or group (this is strongly recommended unless it is strictly |
165 | necessary to use a specific UID or GID). Alternatively, specify an absolute path | |
b938cb90 | 166 | in the file system. In this case, the UID/GID is read from the |
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167 | path's owner/group. This is useful to create users whose UID/GID |
168 | match the owners of pre-existing files (such as SUID or SGID | |
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169 | binaries). |
170 | The syntax <literal><replaceable>uid</replaceable>:<replaceable>gid</replaceable></literal> is also supported to | |
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171 | 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 |
172 | is also supported. | |
4cb41413 | 173 | </para> |
798d3a52 | 174 | |
b938cb90 | 175 | <para>For <varname>m</varname> lines, this field should contain |
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176 | the group name to add to a user to.</para> |
177 | ||
b938cb90 | 178 | <para>For lines of type <varname>r</varname>, this field should |
798d3a52 | 179 | be set to a UID/GID range in the format |
b938cb90 | 180 | <literal>FROM-TO</literal>, where both values are formatted as |
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181 | decimal ASCII numbers. Alternatively, a single UID/GID may be |
182 | specified formatted as decimal ASCII numbers.</para> | |
183 | </refsect2> | |
184 | ||
185 | <refsect2> | |
186 | <title>GECOS</title> | |
187 | ||
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188 | <para>A short, descriptive string for users to be created, enclosed in |
189 | quotation marks. Note that this field may not contain colons.</para> | |
798d3a52 | 190 | |
7b1aaf66 ZJS |
191 | <para>Only applies to lines of type <varname>u</varname> and should otherwise |
192 | be left unset (or <literal>-</literal>).</para> | |
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193 | </refsect2> |
194 | ||
195 | <refsect2> | |
196 | <title>Home Directory</title> | |
197 | ||
7b1aaf66 ZJS |
198 | <para>The home directory for a new system user. If omitted, defaults to the |
199 | root directory.</para> | |
798d3a52 | 200 | |
7b1aaf66 ZJS |
201 | <para>Only applies to lines of type <varname>u</varname> and should otherwise |
202 | be left unset (or <literal>-</literal>). It is recommended to omit this, unless | |
203 | software strictly requires a home directory to be set.</para> | |
204 | </refsect2> | |
205 | ||
206 | <refsect2> | |
207 | <title>Shell</title> | |
208 | ||
209 | <para>The login shell of the user. If not specified, this will be set to | |
210 | <filename>/sbin/nologin</filename>, except if the UID of the user is 0, in | |
211 | which case <filename>/bin/sh</filename> will be used.</para> | |
212 | ||
213 | <para>Only applies to lines of type <varname>u</varname> and should otherwise | |
214 | be left unset (or <literal>-</literal>). It is recommended to omit this, unless | |
215 | a shell different <filename>/sbin/nologin</filename> must be used.</para> | |
798d3a52 | 216 | </refsect2> |
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217 | </refsect1> |
218 | ||
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219 | <refsect1> |
220 | <title>Specifiers</title> | |
221 | ||
222 | <para>Specifiers can be used in the "Name", "ID", "GECOS", "Home directory", and "Shell" fields. | |
223 | An unknown or unresolvable specifier is treated as invalid configuration. | |
224 | The following expansions are understood:</para> | |
225 | <table> | |
226 | <title>Specifiers available</title> | |
227 | <tgroup cols='3' align='left' colsep='1' rowsep='1'> | |
228 | <colspec colname="spec" /> | |
229 | <colspec colname="mean" /> | |
230 | <colspec colname="detail" /> | |
231 | <thead> | |
232 | <row> | |
233 | <entry>Specifier</entry> | |
234 | <entry>Meaning</entry> | |
235 | <entry>Details</entry> | |
236 | </row> | |
237 | </thead> | |
238 | <tbody> | |
239 | <row> | |
240 | <entry><literal>%b</literal></entry> | |
241 | <entry>Boot ID</entry> | |
242 | <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry> | |
243 | </row> | |
244 | <row> | |
245 | <entry><literal>%H</literal></entry> | |
246 | <entry>Host name</entry> | |
247 | <entry>The hostname of the running system.</entry> | |
248 | </row> | |
249 | <row> | |
250 | <entry><literal>%m</literal></entry> | |
251 | <entry>Machine ID</entry> | |
252 | <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry> | |
253 | </row> | |
254 | <row> | |
255 | <entry><literal>%T</literal></entry> | |
256 | <entry>Directory for temporary files</entry> | |
257 | <entry>This is either <filename>/tmp</filename> or the path <literal>$TMPDIR</literal>, <literal>$TEMP</literal> or <literal>$TMP</literal> are set to.</entry> | |
258 | </row> | |
259 | <row> | |
260 | <entry><literal>%v</literal></entry> | |
261 | <entry>Kernel release</entry> | |
262 | <entry>Identical to <command>uname -r</command> output.</entry> | |
263 | </row> | |
264 | <row> | |
265 | <entry><literal>%V</literal></entry> | |
266 | <entry>Directory for larger and persistent temporary files</entry> | |
267 | <entry>This is either <filename>/var/tmp</filename> or the path <literal>$TMPDIR</literal>, <literal>$TEMP</literal> or <literal>$TMP</literal> are set to.</entry> | |
268 | </row> | |
269 | <row> | |
270 | <entry><literal>%%</literal></entry> | |
271 | <entry>Escaped <literal>%</literal></entry> | |
272 | <entry>Single percent sign.</entry> | |
273 | </row> | |
274 | </tbody> | |
275 | </tgroup> | |
276 | </table> | |
277 | </refsect1> | |
278 | ||
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279 | <refsect1> |
280 | <title>Idempotence</title> | |
281 | ||
7b1aaf66 ZJS |
282 | <para>Note that <command>systemd-sysusers</command> will do nothing if the |
283 | specified users or groups already exist or the users are members of specified | |
284 | groups, so normally there is no reason to override | |
285 | <filename>sysusers.d</filename> vendor configuration, except to block certain | |
286 | users or groups from being created.</para> | |
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287 | </refsect1> |
288 | ||
289 | <refsect1> | |
290 | <title>See Also</title> | |
291 | <para> | |
292 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
293 | <citerefentry><refentrytitle>systemd-sysusers</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
294 | </para> | |
295 | </refsect1> | |
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296 | |
297 | </refentry> |