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209 lines
9.8 KiB
XML
209 lines
9.8 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_is_fifo"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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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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</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_socket_sockaddr</refname>
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<refname>sd_is_mq</refname>
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<refname>sd_is_special</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_sockaddr</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>const struct sockaddr *<parameter>addr</parameter></paramdef>
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<paramdef>unsigned <parameter>addr_len</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_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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<funcprototype>
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<funcdef>int <function>sd_is_special</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 to check
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whether the specified file descriptor refers to a FIFO or pipe. If
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the <parameter>path</parameter> parameter is not
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<constant>NULL</constant>, it is checked whether the FIFO is bound
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to the specified file system path.</para>
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<para><function>sd_is_socket()</function> may be called to check
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whether the specified file descriptor refers to a socket. If the
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<parameter>family</parameter> parameter is not
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<constant>AF_UNSPEC</constant>, it is checked whether the socket
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is of the specified family (<constant>AF_UNIX</constant>,
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<constant>AF_INET</constant>, …). If the <parameter>type</parameter>
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parameter is not 0, it is checked whether the socket is of the
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specified type (<constant>SOCK_STREAM</constant>,
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<constant>SOCK_DGRAM</constant>, …). If the
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<parameter>listening</parameter> parameter is positive, it is
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checked whether the socket is in accepting mode, i.e.
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<function>listen()</function> has been called for it. If
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<parameter>listening</parameter> is 0, it is checked whether the
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socket is not in this mode. If the parameter is negative, no such
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check is made. The <parameter>listening</parameter> parameter
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should only 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 similar to
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<function>sd_is_socket()</function>, but optionally checks the
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IPv4 or IPv6 port number the socket is bound to, unless
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<parameter>port</parameter> is zero. For this call
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<parameter>family</parameter> must be passed as either
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<constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
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<constant>AF_INET6</constant>.</para>
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<para><function>sd_is_socket_sockaddr()</function> is similar to
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<function>sd_is_socket_inet()</function>, but checks if the socket is bound to the
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address specified by <parameter>addr</parameter>. The
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<structfield>family</structfield> specified by <parameter>addr</parameter> must be
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either <constant>AF_INET</constant> or <constant>AF_INET6</constant> and
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<parameter>addr_len</parameter> must be large enough for that family. If
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<parameter>addr</parameter> specifies a non-zero port, it is also checked if the
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socket is bound to this port. In addition, for IPv6, if <parameter>addr</parameter>
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specifies non-zero <structfield>sin6_flowinfo</structfield> or
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<structfield>sin6_scope_id</structfield>, it is checked if the socket has the same
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values.</para>
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<para><function>sd_is_socket_unix()</function> is similar to
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<function>sd_is_socket()</function> but optionally checks the
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<constant>AF_UNIX</constant> path the socket is bound to, unless
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the <parameter>path</parameter> parameter is
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<constant>NULL</constant>. For normal file system
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<constant>AF_UNIX</constant> sockets, set the
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<parameter>length</parameter> parameter to 0. For Linux abstract
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namespace sockets, set the <parameter>length</parameter> to the
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size of the address, including the initial 0 byte, and set the
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<parameter>path</parameter> to the initial 0 byte of the socket
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address.</para>
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<para><function>sd_is_mq()</function> may be called to check
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whether the specified file descriptor refers to a POSIX message
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queue. If the <parameter>path</parameter> parameter is not
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<constant>NULL</constant>, it is checked whether the message queue
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is bound to the specified name.</para>
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<para><function>sd_is_special()</function> may be called to check
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whether the specified file descriptor refers to a special file. If
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the <parameter>path</parameter> parameter is not
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<constant>NULL</constant>, it is checked whether the file
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descriptor is bound to the specified filename. Special files in
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this context are character device nodes and files in
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<filename>/proc/</filename> or <filename>/sys/</filename>.</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 errno-style error
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code. If the file descriptor is of the specified type and bound to
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the specified address, a positive return value is returned,
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otherwise zero.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
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<para>Internally, these functions use a combination of
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<citerefentry project='man-pages'><refentrytitle>fstat</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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and
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<citerefentry project='man-pages'><refentrytitle>getsockname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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to check the file descriptor type and where it is bound to.</para>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para><function>sd_is_special()</function> was added in version 209.</para>
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<para><function>sd_is_socket_sockaddr()</function> was added in version 233.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>fifo</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</member>
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</simplelist></para>
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</refsect1>
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</refentry>
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