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1 | <?xml version="1.0"?> |
2 | <!--*-nxml-*--> | |
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3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
4 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
0307f791 | 5 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
e6de49ab | 6 | <refentry id="sysusers.d" conditional='ENABLE_SYSUSERS' |
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7 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
8 | ||
9 | <refentryinfo> | |
10 | <title>sysusers.d</title> | |
11 | <productname>systemd</productname> | |
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12 | </refentryinfo> |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sysusers.d</refentrytitle> | |
16 | <manvolnum>5</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sysusers.d</refname> | |
21 | <refpurpose>Declarative allocation of system users and groups</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
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25 | <para><filename>/etc/sysusers.d/*.conf</filename></para> |
26 | <para><filename>/run/sysusers.d/*.conf</filename></para> | |
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27 | <para><filename>/usr/lib/sysusers.d/*.conf</filename></para> |
28 | </refsynopsisdiv> | |
29 | ||
30 | <refsect1> | |
31 | <title>Description</title> | |
32 | ||
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33 | <para><command>systemd-sysusers</command> uses the files from |
34 | <filename>sysusers.d</filename> directory to create system users and groups and | |
35 | to add users to groups, at package installation or boot time. This tool may be | |
36 | used to allocate system users and groups only, it is not useful for creating | |
37 | non-system (i.e. regular, "human") users and groups, as it accesses | |
38 | <filename>/etc/passwd</filename> and <filename>/etc/group</filename> directly, | |
39 | bypassing any more complex user databases, for example any database involving NIS | |
40 | or LDAP.</para> | |
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41 | </refsect1> |
42 | ||
43 | <refsect1> | |
8165be2e | 44 | <title>Configuration Directories and Precedence</title> |
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45 | |
46 | <para>Each configuration file shall be named in the style of | |
47 | <filename><replaceable>package</replaceable>.conf</filename> or | |
48 | <filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>. | |
49 | The second variant should be used when it is desirable to make it | |
50 | easy to override just this part of configuration.</para> | |
51 | ||
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52 | <para>Files in <filename>/etc/sysusers.d</filename> override files |
53 | with the same name in <filename>/usr/lib/sysusers.d</filename> and | |
54 | <filename>/run/sysusers.d</filename>. Files in | |
55 | <filename>/run/sysusers.d</filename> override files with the same | |
56 | name in <filename>/usr/lib/sysusers.d</filename>. Packages should | |
57 | install their configuration files in | |
58 | <filename>/usr/lib/sysusers.d</filename>. Files in | |
59 | <filename>/etc/sysusers.d</filename> are reserved for the local | |
60 | administrator, who may use this logic to override the | |
61 | configuration files installed by vendor packages. All | |
62 | configuration files are sorted by their filename in lexicographic | |
63 | order, regardless of which of the directories they reside in. If | |
64 | multiple files specify the same path, the entry in the file with | |
65 | the lexicographically earliest name will be applied. All later | |
66 | entries for the same user and group names will be logged as warnings. | |
67 | </para> | |
68 | ||
69 | <para>If the administrator wants to disable a configuration file | |
70 | supplied by the vendor, the recommended way is to place a symlink | |
71 | to <filename>/dev/null</filename> in | |
72 | <filename>/etc/sysusers.d/</filename> bearing the same filename. | |
73 | </para> | |
74 | </refsect1> | |
75 | ||
76 | <refsect1> | |
77 | <title>Configuration File Format</title> | |
78 | ||
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79 | <para>The file format is one line per user or group containing name, ID, GECOS |
80 | field description, home directory, and login shell:</para> | |
798d3a52 | 81 | |
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82 | <programlisting>#Type Name ID GECOS Home directory Shell |
83 | u httpd 404 "HTTP User" | |
84 | u authd /usr/bin/authd "Authorization user" | |
85 | u postgres - "Postgresql Database" /var/lib/pgsql /usr/libexec/postgresdb | |
86 | g input - - | |
87 | m authd input | |
88 | u root 0 "Superuser" /root /bin/zsh</programlisting> | |
21236ab5 | 89 | |
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90 | <para>Empty lines and lines beginning with the <literal>#</literal> character are ignored, and may be used for |
91 | commenting.</para> | |
92 | ||
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93 | <refsect2> |
94 | <title>Type</title> | |
95 | ||
96 | <para>The type consists of a single letter. The following line | |
97 | types are understood:</para> | |
98 | ||
99 | <variablelist> | |
100 | <varlistentry> | |
101 | <term><varname>u</varname></term> | |
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102 | <listitem><para>Create a system user and group of the specified name should |
103 | they not exist yet. The user's primary group will be set to the group | |
104 | bearing the same name. The account will be created disabled, so that logins | |
105 | are not allowed.</para></listitem> | |
798d3a52 ZJS |
106 | </varlistentry> |
107 | ||
108 | <varlistentry> | |
109 | <term><varname>g</varname></term> | |
110 | <listitem><para>Create a system group of the specified name | |
111 | should it not exist yet. Note that <varname>u</varname> | |
112 | implicitly create a matching group. The group will be | |
113 | created with no password set.</para></listitem> | |
114 | </varlistentry> | |
115 | ||
116 | <varlistentry> | |
117 | <term><varname>m</varname></term> | |
118 | <listitem><para>Add a user to a group. If the user or group | |
cd72d204 | 119 | do not exist yet, they will be implicitly |
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120 | created.</para></listitem> |
121 | </varlistentry> | |
122 | ||
123 | <varlistentry> | |
124 | <term><varname>r</varname></term> | |
125 | <listitem><para>Add a range of numeric UIDs/GIDs to the pool | |
126 | to allocate new UIDs and GIDs from. If no line of this type | |
b938cb90 | 127 | is specified, the range of UIDs/GIDs is set to some |
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128 | compiled-in default. Note that both UIDs and GIDs are |
129 | allocated from the same pool, in order to ensure that users | |
130 | and groups of the same name are likely to carry the same | |
131 | numeric UID and GID.</para></listitem> | |
132 | </varlistentry> | |
133 | ||
134 | </variablelist> | |
135 | </refsect2> | |
136 | ||
137 | <refsect2> | |
138 | <title>Name</title> | |
139 | ||
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140 | <para>The name field specifies the user or group name. The specified name must consist only of the characters a-z, |
141 | A-Z, 0-9, <literal>_</literal> and <literal>-</literal>, except for the first character which must be one of a-z, | |
142 | A-Z or <literal>_</literal> (i.e. numbers and <literal>-</literal> are not permitted as first character). The | |
143 | user/group name must have at least one character, and at most 31.</para> | |
144 | ||
145 | <para>It is strongly recommended to pick user and group names that are unlikely to clash with normal users | |
146 | created by the administrator. A good scheme to guarantee this is by prefixing all system and group names with the | |
147 | underscore, and avoiding too generic names.</para> | |
798d3a52 | 148 | |
b938cb90 | 149 | <para>For <varname>m</varname> lines, this field should contain |
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150 | the user name to add to a group.</para> |
151 | ||
b938cb90 | 152 | <para>For lines of type <varname>r</varname>, this field should |
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153 | be set to <literal>-</literal>.</para> |
154 | </refsect2> | |
155 | ||
156 | <refsect2> | |
157 | <title>ID</title> | |
158 | ||
b938cb90 JE |
159 | <para>For <varname>u</varname> and <varname>g</varname>, the |
160 | numeric 32-bit UID or GID of the user/group. Do not use IDs 65535 | |
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161 | or 4294967295, as they have special placeholder meanings. |
162 | Specify <literal>-</literal> for automatic UID/GID allocation | |
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163 | for the user or group (this is strongly recommended unless it is strictly |
164 | necessary to use a specific UID or GID). Alternatively, specify an absolute path | |
b938cb90 | 165 | in the file system. In this case, the UID/GID is read from the |
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166 | path's owner/group. This is useful to create users whose UID/GID |
167 | match the owners of pre-existing files (such as SUID or SGID | |
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168 | binaries). |
169 | The syntax <literal><replaceable>uid</replaceable>:<replaceable>gid</replaceable></literal> is also supported to | |
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170 | 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 |
171 | is also supported. | |
4cb41413 | 172 | </para> |
798d3a52 | 173 | |
b938cb90 | 174 | <para>For <varname>m</varname> lines, this field should contain |
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175 | the group name to add to a user to.</para> |
176 | ||
b938cb90 | 177 | <para>For lines of type <varname>r</varname>, this field should |
798d3a52 | 178 | be set to a UID/GID range in the format |
b938cb90 | 179 | <literal>FROM-TO</literal>, where both values are formatted as |
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180 | decimal ASCII numbers. Alternatively, a single UID/GID may be |
181 | specified formatted as decimal ASCII numbers.</para> | |
182 | </refsect2> | |
183 | ||
184 | <refsect2> | |
185 | <title>GECOS</title> | |
186 | ||
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187 | <para>A short, descriptive string for users to be created, enclosed in |
188 | quotation marks. Note that this field may not contain colons.</para> | |
798d3a52 | 189 | |
7b1aaf66 ZJS |
190 | <para>Only applies to lines of type <varname>u</varname> and should otherwise |
191 | be left unset (or <literal>-</literal>).</para> | |
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192 | </refsect2> |
193 | ||
194 | <refsect2> | |
195 | <title>Home Directory</title> | |
196 | ||
7b1aaf66 ZJS |
197 | <para>The home directory for a new system user. If omitted, defaults to the |
198 | root directory.</para> | |
798d3a52 | 199 | |
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200 | <para>Only applies to lines of type <varname>u</varname> and should otherwise |
201 | be left unset (or <literal>-</literal>). It is recommended to omit this, unless | |
202 | software strictly requires a home directory to be set.</para> | |
203 | </refsect2> | |
204 | ||
205 | <refsect2> | |
206 | <title>Shell</title> | |
207 | ||
208 | <para>The login shell of the user. If not specified, this will be set to | |
209 | <filename>/sbin/nologin</filename>, except if the UID of the user is 0, in | |
210 | which case <filename>/bin/sh</filename> will be used.</para> | |
211 | ||
212 | <para>Only applies to lines of type <varname>u</varname> and should otherwise | |
213 | be left unset (or <literal>-</literal>). It is recommended to omit this, unless | |
214 | a shell different <filename>/sbin/nologin</filename> must be used.</para> | |
798d3a52 | 215 | </refsect2> |
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216 | </refsect1> |
217 | ||
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218 | <refsect1> |
219 | <title>Specifiers</title> | |
220 | ||
221 | <para>Specifiers can be used in the "Name", "ID", "GECOS", "Home directory", and "Shell" fields. | |
222 | An unknown or unresolvable specifier is treated as invalid configuration. | |
223 | The following expansions are understood:</para> | |
224 | <table> | |
225 | <title>Specifiers available</title> | |
226 | <tgroup cols='3' align='left' colsep='1' rowsep='1'> | |
227 | <colspec colname="spec" /> | |
228 | <colspec colname="mean" /> | |
229 | <colspec colname="detail" /> | |
230 | <thead> | |
231 | <row> | |
232 | <entry>Specifier</entry> | |
233 | <entry>Meaning</entry> | |
234 | <entry>Details</entry> | |
235 | </row> | |
236 | </thead> | |
237 | <tbody> | |
238 | <row> | |
239 | <entry><literal>%b</literal></entry> | |
240 | <entry>Boot ID</entry> | |
241 | <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry> | |
242 | </row> | |
243 | <row> | |
244 | <entry><literal>%H</literal></entry> | |
245 | <entry>Host name</entry> | |
246 | <entry>The hostname of the running system.</entry> | |
247 | </row> | |
248 | <row> | |
249 | <entry><literal>%m</literal></entry> | |
250 | <entry>Machine ID</entry> | |
251 | <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> | |
252 | </row> | |
253 | <row> | |
254 | <entry><literal>%T</literal></entry> | |
255 | <entry>Directory for temporary files</entry> | |
256 | <entry>This is either <filename>/tmp</filename> or the path <literal>$TMPDIR</literal>, <literal>$TEMP</literal> or <literal>$TMP</literal> are set to.</entry> | |
257 | </row> | |
258 | <row> | |
259 | <entry><literal>%v</literal></entry> | |
260 | <entry>Kernel release</entry> | |
261 | <entry>Identical to <command>uname -r</command> output.</entry> | |
262 | </row> | |
263 | <row> | |
264 | <entry><literal>%V</literal></entry> | |
265 | <entry>Directory for larger and persistent temporary files</entry> | |
266 | <entry>This is either <filename>/var/tmp</filename> or the path <literal>$TMPDIR</literal>, <literal>$TEMP</literal> or <literal>$TMP</literal> are set to.</entry> | |
267 | </row> | |
268 | <row> | |
269 | <entry><literal>%%</literal></entry> | |
270 | <entry>Escaped <literal>%</literal></entry> | |
271 | <entry>Single percent sign.</entry> | |
272 | </row> | |
273 | </tbody> | |
274 | </tgroup> | |
275 | </table> | |
276 | </refsect1> | |
277 | ||
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278 | <refsect1> |
279 | <title>Idempotence</title> | |
280 | ||
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281 | <para>Note that <command>systemd-sysusers</command> will do nothing if the |
282 | specified users or groups already exist or the users are members of specified | |
283 | groups, so normally there is no reason to override | |
284 | <filename>sysusers.d</filename> vendor configuration, except to block certain | |
285 | users or groups from being created.</para> | |
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286 | </refsect1> |
287 | ||
288 | <refsect1> | |
289 | <title>See Also</title> | |
290 | <para> | |
291 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
292 | <citerefentry><refentrytitle>systemd-sysusers</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
293 | </para> | |
294 | </refsect1> | |
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295 | |
296 | </refentry> |