16dad32e43
As you likely know, Arch Linux is in the process of moving to systemd. So I was reading through the various systemd docs and quickly became baffled by this new abbreviation "resp.", which I've never seen before in my English-mother-tongue life. Some quick Googling turned up a reference: <http://www.transblawg.eu/index.php?/archives/870-Resp.-and-other-non-existent-English-wordsNicht-existente-englische-Woerter.html> I guess it's a literal translation of the German "Beziehungsweise", but English doesn't work the same way. The word "respectively" is used exclusively to provide an ordering connection between two lists. E.g. "the prefixes k, M, and G refer to kilo-, mega-, and giga-, respectively." It is also never abbreviated to "resp." So the sentence "Sets the default output resp. error output for all services and sockets" makes no sense to a natural English speaker. This patch removes all instances of "resp." in the man pages and replaces them with sentences which are much more clear and, hopefully, grammatically valid. In almost all instances, it was simply replacing "resp." with "or," which the original author (Lennart?) could probably just do in the future. The only other instances of "resp." are in the src/ subtree, which I don't feel privileged to correct. Signed-off-by: Andrew Eikum <aeikum@codeweavers.com>
205 lines
10 KiB
XML
205 lines
10 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_listen_fds">
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<refentryinfo>
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<title>sd_listen_fds</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_listen_fds</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_listen_fds</refname>
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<refname>SD_LISTEN_FDS_START</refname>
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<refpurpose>Check for file descriptors passed by the system manager</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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<funcsynopsisinfo>#define SD_LISTEN_FDS_START 3</funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_listen_fds</function></funcdef>
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<paramdef>int <parameter>unset_environment</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_listen_fds()</function> shall be
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called by a daemon to check for file descriptors
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passed by the init system as part of the socket-based
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activation logic.</para>
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<para>If the <parameter>unset_environment</parameter>
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parameter is non-zero
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<function>sd_listen_fds()</function> will unset the
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<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname>
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environment variables before returning (regardless
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whether the function call itself succeeded or
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not). Further calls to
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<function>sd_listen_fds()</function> will then fail,
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but the variables are no longer inherited by child
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processes.</para>
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<para>If a daemon receives more than one file
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descriptor, they will be passed in the same order as
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configured in the systemd socket definition
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file. Nonetheless it is recommended to verify the
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correct socket types before using them. To simplify
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this checking the functions
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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are provided. In order to maximize flexibility it is
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recommended to make these checks as loose as possible
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without allowing incorrect setups. i.e. often the
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actual port number a socket is bound to matters little
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for the service to work, hence it should not be
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verified. On the other hand, whether a socket is a
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datagram or stream socket matters a lot for the most
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common program logics and should be checked.</para>
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<para>This function call will set the FD_CLOEXEC flag
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for all passed file descriptors to avoid further
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inheritance to children of the calling process.</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, this call returns a negative
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errno-style error code. If
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<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname>
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was not set or was not correctly set for this daemon and
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hence no file descriptors were received, 0 is
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returned. Otherwise the number of file descriptors
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passed is returned. The application may find them
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starting with file descriptor SD_LISTEN_FDS_START,
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i.e. file descriptor 3.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>This function is 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 algorithm it
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implements is simple, and can easily be reimplemented
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in daemons if it is important to support this
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interface without using the reference
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implementation.</para>
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<para>Internally, this function checks whether the
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<varname>$LISTEN_PID</varname> environment variable
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equals the daemon PID. If not, it returns
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immediately. Otherwise it parses the number passed in
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the <varname>$LISTEN_FDS</varname> environment
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variable, then sets the FD_CLOEXEC flag for the parsed
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number of file descriptors starting from
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SD_LISTEN_FDS_START. Finally it returns the parsed
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number.</para>
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<para>For details about the algorithm 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/libsystemd-daemon/sd-daemon.c"/>
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and <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_listen_fds()</function> is
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implemented in the reference implementation's
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<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>3</manvolnum></citerefentry>.</para>
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<para>If the reference implementation is used as
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drop-in files and -DDISABLE_SYSTEMD is set during
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compilation this function will always return 0 and
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otherwise become a NOP.</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist>
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<varlistentry>
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<term><varname>$LISTEN_PID</varname></term>
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<term><varname>$LISTEN_FDS</varname></term>
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<listitem><para>Set by the init system
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for supervised processes that use
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socket-based activation. This
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environment variable specifies the
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data
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<function>sd_listen_fds()</function>
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parses. See above for
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details.</para></listitem>
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</varlistentry>
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</variablelist>
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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>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</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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