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5aded36978
It is annoying when we have dead links on fd.o. Add project='man-pages|die-net|archlinux' to <citerefentry>-ies. In generated html, add external links to http://man7.org/linux/man-pages/man, http://linux.die.net/man/, https://www.archlinux.org/. By default, pages in sections 2 and 4 go to man7, since Michael Kerrisk is the autorative source on kernel related stuff. The rest of links goes to linux.die.net, because they have the manpages. Except for the pacman stuff, since it seems to be only available from archlinux.org. Poor gummiboot gets no link, because gummitboot(8) ain't to be found on the net. According to common wisdom, that would mean that it does not exist. But I have seen Kay using it, so I know it does, and deserves to be found. Can somebody be nice and put it up somewhere?
246 lines
9.8 KiB
XML
246 lines
9.8 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 2014 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_event_add_time" conditional="ENABLE_KDBUS">
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<refentryinfo>
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<title>sd_event_add_time</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_event_add_time</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_event_add_time</refname>
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<refname>sd_event_source_get_time</refname>
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<refname>sd_event_source_set_time</refname>
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<refname>sd_event_source_get_time_accuracy</refname>
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<refname>sd_event_source_set_time_accuracy</refname>
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<refname>sd_event_source_get_time_clock</refname>
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<refpurpose>Add a timer event source to an event loop</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_event_add_time</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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<paramdef>sd_event_source **<parameter>source</parameter></paramdef>
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<paramdef>clockid_t <parameter>clock</parameter></paramdef>
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<paramdef>uint64_t <parameter>usec</parameter></paramdef>
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<paramdef>uint64_t <parameter>accuracy</parameter></paramdef>
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<paramdef>sd_event_time_handler_t <parameter>handler</parameter></paramdef>
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<paramdef>void *<parameter>userdata</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_source_get_time</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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<paramdef>usec_t *<parameter>usec</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_source_set_time</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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<paramdef>usec_t <parameter>usec</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_source_get_time_accuracy</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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<paramdef>usec_t *<parameter>usec</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_source_set_time_accuracy</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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<paramdef>usec_t <parameter>usec</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_source_get_time_clock</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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<paramdef>clockid_t *<parameter>clock</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_event_add_time()</function> adds a new timer
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event source to an event loop object. The event loop is specified
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in <parameter>event</parameter>, the event source is returned in
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the <parameter>source</parameter> parameter. The
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<parameter>clock</parameter> parameter takes a clock identifier,
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one of <constant>CLOCK_REALTIME</constant>,
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<constant>CLOCK_MONOTONIC</constant> and
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<constant>CLOCK_BOOTTIME_ALARM</constant>. See
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<citerefentry><refentrytitle>timerfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for details regarding the various types of clocks. The
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<parameter>usec</parameter> parameter takes a time value in
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microseconds, relative to the clock's epoch specifying when the
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timer shall elapse the earliest. The
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<parameter>accuracy</parameter> parameter takes an additional
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accuracy value in microseconds specifying a time the timer event
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may be delayed. Specify 0 for selecting the default accuracy
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(250ms). Specify 1 for most accurate timers. Consider specifying
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60000000 or larger (1h) for long-running events that may be
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delayed substantially. Picking higher accuracy values allows the
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system to coalesce timer events more aggressively, thus improving
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power efficiency. The <parameter>handler</parameter> shall
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reference a function to call when the timer elapses. The handler
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function will be passed the <parameter>userdata</parameter>
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pointer, which may be chosen freely by the caller. The handler is
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also passed the configured time it was triggered, however it might
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actually have been called at a slightly later time, subject to the
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specified accuracy value, the kernel timer slack (see
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<citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>)
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and additional scheduling latencies. By default, the timer will
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elapse once (SD_EVENT_ONESHOT), but this may be changed with
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<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
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the handler function returns a negative error code, it will be
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disabled after the invocation, even if SD_EVENT_ON mode is set.
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</para>
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<para><function>sd_event_source_get_time()</function> retrieves
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the configured time value of a timer event source created
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previously with <function>sd_event_add_time()</function>. It takes
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the event source object and a pointer to a variable to store the
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time in microseconds in.</para>
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<para><function>sd_event_source_set_time()</function> changes the
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configured time value of a timer event source created previously
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with <function>sd_event_add_time()</function>. It takes the event
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source object and a time relative to the selected clock's
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epoch, in microseconds.</para>
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<para><function>sd_event_source_get_time_accuracy()</function>
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retrieves the configured accuracy value of a timer event source
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created previously with <function>sd_event_add_time()</function>. It
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takes the event source object and a pointer to a variable to store
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the accuracy in microseconds in.</para>
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<para><function>sd_event_source_set_time_accuracy()</function>
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changes the configured accuracy of a timer event source created
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previously with <function>sd_event_add_time()</function>. It takes
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the event source object and an accuracy, in microseconds.</para>
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<para><function>sd_event_source_get_time_clock()</function>
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retrieves the configured clock of a timer event source created
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previously with <function>sd_event_add_time()</function>. It takes
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the event source object and a pointer to a variable to store the
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clock identifier in.</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 success, these functions return 0 or a positive
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integer. On failure, they return a negative errno-style error
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code. </para>
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</refsect1>
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<refsect1>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><varname>-ENOMEM</varname></term>
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<listitem><para>Not enough memory to allocate object.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>-EINVAL</varname></term>
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<listitem><para>An invalid argument has been passed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>-ESTALE</varname></term>
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<listitem><para>The event loop is already terminated.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>-ECHILD</varname></term>
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<listitem><para>The event loop has been created in a different process.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>-ENOTSUP</varname></term>
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<listitem><para>The selected clock is not supported by the event loop implementation.</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>Notes</title>
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<para><function>sd_event_add_time()</function> and the other functions
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described here are available as a shared library, which can be
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compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</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-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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