mirror of
https://github.com/AuxXxilium/eudev.git
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5430f7f2bc
We finally got the OK from all contributors with non-trivial commits to relicense systemd from GPL2+ to LGPL2.1+. Some udev bits continue to be GPL2+ for now, but we are looking into relicensing them too, to allow free copy/paste of all code within systemd. The bits that used to be MIT continue to be MIT. The big benefit of the relicensing is that closed source code may now link against libsystemd-login.so and friends.
218 lines
11 KiB
XML
218 lines
11 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_is_fifo">
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<refentryinfo>
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<title>sd_is_fifo</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_is_fifo</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_is_fifo</refname>
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<refname>sd_is_socket</refname>
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<refname>sd_is_socket_inet</refname>
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<refname>sd_is_socket_unix</refname>
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<refname>sd_is_mq</refname>
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<refpurpose>Check the type of a file descriptor</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_is_fifo</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_is_socket</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>family</parameter></paramdef>
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<paramdef>int <parameter>type</parameter></paramdef>
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<paramdef>int <parameter>listening</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_is_socket_inet</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>family</parameter></paramdef>
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<paramdef>int <parameter>type</parameter></paramdef>
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<paramdef>int <parameter>listening</parameter></paramdef>
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<paramdef>uint16_t <parameter>port</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_is_socket_unix</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>type</parameter></paramdef>
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<paramdef>int <parameter>listening</parameter></paramdef>
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<paramdef>const char* <parameter>path</parameter></paramdef>
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<paramdef>size_t <parameter>length</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_is_mq</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_is_fifo()</function> may be called
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to check whether the specified file descriptor refers
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to a FIFO or pipe. If the <parameter>path</parameter>
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parameter is not NULL, it is checked whether the FIFO
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is bound to the specified file system path.</para>
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<para><function>sd_is_socket()</function> may be
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called to check whether the specified file descriptor
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refers to a socket. It the
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<parameter>family</parameter> parameter is not
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AF_UNSPEC it is checked whether the socket is of the
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specified family (AF_UNIX, AF_INET, ...). If the
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<parameter>type</parameter> parameter is not 0 it is
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checked whether the socket is of the specified type
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(SOCK_STREAM, SOCK_DGRAM, ...). If the
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<parameter>listening</parameter> parameter is positive
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it is checked whether the socket is in accepting mode,
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i.e. <function>listen()</function> has been called for
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it. If <parameter>listening</parameter> is 0, it is
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checked whether the socket is not in this mode. If the
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parameter is negative, no such check is made. The
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<parameter>listening</parameter> parameter should only
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be used for stream sockets and should be set to a
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negative value otherwise.</para>
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<para><function>sd_is_socket_inet()</function> is
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similar to <function>sd_is_socket()</function>, but
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optionally checks the IPv4 or IPv6 port number the
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socket is bound to, unless <parameter>port</parameter>
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is zero. For this call <parameter>family</parameter>
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must be passed as either AF_UNSPEC, AF_INET or
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AF_INET6.</para>
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<para><function>sd_is_socket_unix()</function> is
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similar to <function>sd_is_socket()</function>, but
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optionally checks the AF_UNIX path the socket is bound
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to, unless the <parameter>path</parameter> parameter
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is NULL. For normal file system AF_UNIX sockets set
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the <parameter>length</parameter> parameter to 0. For
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Linux abstract namespace sockets set the
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<parameter>length</parameter> to the size of the
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address, including the initial 0 byte and set
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<parameter>path</parameter> to the initial 0 byte of
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the socket address.</para>
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<para><function>sd_is_mq()</function> may be called to
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check whether the specified file descriptor refers to
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a POSIX message queue. If the
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<parameter>path</parameter> parameter is not NULL, it
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is checked whether the message queue is bound to the
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specified name.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On failure, these calls return a negative
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errno-style error code. If the file descriptor is of
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the specified type and bound to the specified address
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a positive return value is returned, otherwise
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zero.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>These functions are provided by the reference
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implementation of APIs for new-style daemons and
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distributed with the systemd package. The algorithms
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they implement are simple, and can easily be
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reimplemented in daemons if it is important to support
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this interface without using the reference
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implementation.</para>
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<para>Internally, these function use a combination of
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<filename>fstat()</filename> and
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<filename>getsockname()</filename> to check the file
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descriptor type and where it is bound to.</para>
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<para>For details about the algorithms check the
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liberally licensed reference implementation sources:
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<ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/sd-daemon.c"/>
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resp. <ulink
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url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para>
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<para><function>sd_is_fifo()</function> and the
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related functions are implemented in the reference
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implementation's <filename>sd-daemon.c</filename> and
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<filename>sd-daemon.h</filename> files. These
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interfaces are available as shared library, which can
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be compiled and linked to with the
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<literal>libsystemd-daemon</literal>
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<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file. Alternatively, applications consuming these APIs
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may copy the implementation into their source
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tree. For more details about the reference
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implementation see
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<citerefentry><refentrytitle>sd_daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
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<para>These functions continue to work as described,
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even if -DDISABLE_SYSTEMD is set during
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compilation.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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