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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
176 lines
6.6 KiB
XML
176 lines
6.6 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 2013 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_watchdog_enabled"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_watchdog_enabled</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_watchdog_enabled</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_watchdog_enabled</refname>
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<refpurpose>Check whether the service manager expects watchdog keep-alive notifications from a service</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_watchdog_enabled</function></funcdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>uint64_t *<parameter>usec</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_watchdog_enabled()</function> may be called by
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a service to detect whether the service manager expects regular
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keep-alive watchdog notification events from it, and the timeout
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after which the manager will act on the service if it did not get
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such a notification.</para>
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<para>If the <varname>$WATCHDOG_USEC</varname> environment
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variable is set, and the <varname>$WATCHDOG_PID</varname> variable
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is unset or set to the PID of the current process, the service
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manager expects notifications from this process. The manager will
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usually terminate a service when it does not get a notification
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message within the specified time after startup and after each
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previous message. It is recommended that a daemon sends a
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keep-alive notification message to the service manager every half
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of the time returned here. Notification messages may be sent with
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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with a message string of <literal>WATCHDOG=1</literal>.</para>
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<para>If the <parameter>unset_environment</parameter> parameter is
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non-zero, <function>sd_watchdog_enabled()</function> will unset
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the <varname>$WATCHDOG_USEC</varname> and
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<varname>$WATCHDOG_PID</varname> environment variables before
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returning (regardless of whether the function call itself
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succeeded or not). Those variables are no longer inherited by
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child processes. Further calls to
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<function>sd_watchdog_enabled()</function> will also return with
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zero.</para>
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<para>If the <parameter>usec</parameter> parameter is non-NULL,
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<function>sd_watchdog_enabled()</function> will write the timeout
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in µs for the watchdog logic to it.</para>
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<para>To enable service supervision with the watchdog logic, use
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<varname>WatchdogSec=</varname> in service files. See
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</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 errno-style error
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code. If the service manager expects watchdog keep-alive
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notification messages to be sent, > 0 is returned, otherwise 0
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is returned. Only if the return value is > 0, the
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<parameter>usec</parameter> parameter is valid after the
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call.</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, this functions parses the
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<varname>$WATCHDOG_PID</varname> and
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<varname>$WATCHDOG_USEC</varname> environment variable. The call
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will ignore these variables if <varname>$WATCHDOG_PID</varname>
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does not contain the PID of the current process, under the
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assumption that in that case, the variables were set for a
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different process further up the process tree.</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist class='environment-variables'>
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<varlistentry>
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<term><varname>$WATCHDOG_PID</varname></term>
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<listitem><para>Set by the system manager for supervised
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process for which watchdog support is enabled, and contains
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the PID of that process. See above for
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details.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>$WATCHDOG_USEC</varname></term>
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<listitem><para>Set by the system manager for supervised
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process for which watchdog support is enabled, and contains
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the watchdog timeout in µs See above for
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details.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para>The watchdog functionality and the
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<varname>$WATCHDOG_USEC</varname> variable were added in
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systemd-41.</para>
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<para><function>sd_watchdog_enabled()</function> function was
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added in systemd-209. Since that version the
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<varname>$WATCHDOG_PID</varname> variable is also set.</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>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>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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