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sysusers: allow overrides in /etc and /run 

An administrator might want to block a certain sysusers config file from
being executed, e.g. to block the creation of a certain user.

Only a relatively short description is added in the man page, since
overrides should be relatively rare.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2014-07-10 08:50:32 -04:00
parent cabb0bc6b1
commit 938a560b76
2 changed files with 46 additions and 19 deletions
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63
man/sysusers.d.xml
View File

@ -53,32 +53,28 @@
<title>Description</title>
<para><command>systemd-sysusers</command> uses the
files from <filename>/usr/lib/sysusers.d/</filename>
files from <filename>sysusers.d</filename> directory
to create system users and groups at package
installation or boot time. This tool may be used for
allocating system users and groups only, it is not
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
accessed <filename>/etc/passwd</filename> and
accesses <filename>/etc/passwd</filename> and
<filename>/etc/group</filename> directly, bypassing
any more complex user database, for example any
any more complex user databases, for example any
database involving NIS or LDAP.</para>
</refsect1>
<refsect1>
<title>File Format</title>
<title>Configuration Format</title>
<para>Each file shall be named in the style of
<filename><replaceable>package</replaceable>.conf</filename>.</para>
<para>All files are sorted by their filename in
lexicographic order, regardless of which of the
directories they reside in. If multiple files specify
the same user or group, the entry in the file with the
lexicographically earliest name will be applied, all
all other conflicting entries will be logged as
errors. Users and groups are
processed in the order they are listed.</para>
<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 and GECOS field description:</para>
@ -192,11 +188,40 @@ m authd input</programlisting>
</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>systemd-sysusers</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>

2
src/sysusers/sysusers.c
View File

@ -62,6 +62,8 @@ typedef struct Item {
static char *arg_root = NULL;
static const char conf_file_dirs[] =
"/etc/sysusers.d\0"
"/run/sysusers.d\0"
"/usr/local/lib/sysusers.d\0"
"/usr/lib/sysusers.d\0"
#ifdef HAVE_SPLIT_USR