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681eb9cf2b
In particular, use /lib/systemd instead of /usr/lib/systemd in distributions like Debian which still have not adopted a /usr merge setup. Use XML entities from man/custom-entities.ent to replace configured paths while doing XSLT processing of the original XML files. There was precedent of some files (such as systemd.generator.xml) which were already using this approach. This addresses most of the (manual) fixes from this patch: http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220 The idea of using generic XML entities was presented here: http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html This patch solves almost all the issues, with the exception of: - Path to /bin/mount and /bin/umount. - Generic statements about preference of /lib over /etc. These will be handled separately by follow up patches. Tested: - With default configure settings, ran "make install" to two separate directories and compared the output to confirm they matched exactly. - Used a set of configure flags including $CONFFLAGS from Debian: http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules Installed the tree and confirmed the paths use /lib/systemd instead of /usr/lib/systemd and that no other unexpected differences exist. - Confirmed that `make distcheck` still passes.
380 lines
15 KiB
XML
380 lines
15 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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<!ENTITY % entities SYSTEM "custom-entities.ent" >
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%entities;
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]>
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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_notify"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_notify</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_notify</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_notify</refname>
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<refname>sd_notifyf</refname>
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<refname>sd_pid_notify</refname>
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<refname>sd_pid_notifyf</refname>
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<refname>sd_pid_notify_with_fds</refname>
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<refpurpose>Notify service manager about start-up completion and other service status changes</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_notify</function></funcdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>const char *<parameter>state</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_notifyf</function></funcdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_notify</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>const char *<parameter>state</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_notifyf</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_notify_with_fds</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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<paramdef>const char *<parameter>state</parameter></paramdef>
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<paramdef>const int *<parameter>fds</parameter></paramdef>
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<paramdef>unsigned <parameter>n_fds</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_notify()</function> may be called by a service
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to notify the service manager about state changes. It can be used
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to send arbitrary information, encoded in an
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environment-block-like string. Most importantly it can be used for
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start-up completion notification.</para>
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<para>If the <parameter>unset_environment</parameter> parameter is
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non-zero, <function>sd_notify()</function> will unset the
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<varname>$NOTIFY_SOCKET</varname> environment variable before
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returning (regardless of whether the function call itself
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succeeded or not). Further calls to
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<function>sd_notify()</function> will then fail, but the variable
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is no longer inherited by child processes.</para>
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<para>The <parameter>state</parameter> parameter should contain a
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newline-separated list of variable assignments, similar in style
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to an environment block. A trailing newline is implied if none is
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specified. The string may contain any kind of variable
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assignments, but the following shall be considered
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well-known:</para>
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<variablelist>
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<varlistentry>
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<term>READY=1</term>
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<listitem><para>Tells the service manager that service startup
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is finished. This is only used by systemd if the service
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definition file has Type=notify set. Since there is little
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value in signaling non-readiness, the only value services
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should send is <literal>READY=1</literal> (i.e.
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<literal>READY=0</literal> is not defined).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>RELOADING=1</term>
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<listitem><para>Tells the service manager that the service is
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reloading its configuration. This is useful to allow the
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service manager to track the service's internal state, and
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present it to the user. Note that a service that sends this
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notification must also send a <literal>READY=1</literal>
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notification when it completed reloading its
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configuration.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>STOPPING=1</term>
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<listitem><para>Tells the service manager that the service is
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beginning its shutdown. This is useful to allow the service
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manager to track the service's internal state, and present it
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to the user.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>STATUS=...</term>
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<listitem><para>Passes a single-line UTF-8 status string back
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to the service manager that describes the service state. This
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is free-form and can be used for various purposes: general
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state feedback, fsck-like programs could pass completion
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percentages and failing programs could pass a human readable
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error message. Example: <literal>STATUS=Completed 66% of file
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system check...</literal></para></listitem>
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</varlistentry>
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<varlistentry>
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<term>ERRNO=...</term>
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<listitem><para>If a service fails, the errno-style error
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code, formatted as string. Example: <literal>ERRNO=2</literal>
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for ENOENT.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>BUSERROR=...</term>
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<listitem><para>If a service fails, the D-Bus error-style
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error code. Example:
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<literal>BUSERROR=org.freedesktop.DBus.Error.TimedOut</literal></para></listitem>
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</varlistentry>
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<varlistentry>
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<term>MAINPID=...</term>
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<listitem><para>The main process ID (PID) of the service, in
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case the service manager did not fork off the process itself.
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Example: <literal>MAINPID=4711</literal></para></listitem>
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</varlistentry>
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<varlistentry>
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<term>WATCHDOG=1</term>
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<listitem><para>Tells the service manager to update the
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watchdog timestamp. This is the keep-alive ping that services
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need to issue in regular intervals if
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<varname>WatchdogSec=</varname> is enabled for it. See
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for information how to enable this functionality and
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<citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for the details of how the service can check if the the
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watchdog is enabled. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term>FDSTORE=1</term>
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<listitem><para>Stores additional file descriptors in the
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service manager. File descriptors sent this way will be
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maintained per-service by the service manager and be passed
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again using the usual file descriptor passing logic on the
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next invocation of the service (see
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<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
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This is useful for implementing service restart schemes where
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services serialize their state to <filename>/run</filename>,
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push their file descriptors to the system manager, and are
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then restarted, retrieving their state again via socket
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passing and <filename>/run</filename>. Note that the service
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manager will accept messages for a service only if
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<varname>FileDescriptorStoreMax=</varname> is set to non-zero
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for it (defaults to zero). See
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details. Multiple arrays of file descriptors may be sent
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in separate messages, in which case the arrays are combined.
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Note that the service manager removes duplicate file
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descriptors before passing them to the service. Use
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<function>sd_pid_notify_with_fds()</function> to send messages
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with <literal>FDSTORE=1</literal>, see
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below.</para></listitem>
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</varlistentry>
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</variablelist>
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<para>It is recommended to prefix variable names that are not
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listed above with <varname>X_</varname> to avoid namespace
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clashes.</para>
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<para>Note that systemd will accept status data sent from a
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service only if the <varname>NotifyAccess=</varname> option is
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correctly set in the service definition file. 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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<para><function>sd_notifyf()</function> is similar to
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<function>sd_notify()</function> but takes a
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<function>printf()</function>-like format string plus
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arguments.</para>
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<para><function>sd_pid_notify()</function> and
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<function>sd_pid_notifyf()</function> are similar to
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<function>sd_notify()</function> and
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<function>sd_notifyf()</function> but take a process ID (PID) to
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use as originating PID for the message as first argument. This is
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useful to send notification messages on behalf of other processes,
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provided the appropriate privileges are available. If the PID
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argument is specified as 0 the process ID of the calling process
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is used, in which case the calls are fully equivalent to
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<function>sd_notify()</function> and
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<function>sd_notifyf()</function>.</para>
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<para><function>sd_pid_notify_with_fds()</function> is similar to
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<function>sd_pid_notify()</function> but takes an additional array
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of file descriptors. These file descriptors are sent along the
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notification message to the service manager. This is particularly
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useful for sending <literal>FDSTORE=1</literal> messages, as
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described above. The additional arguments are a pointer to the
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file descriptor array plus the number of file descriptors in the
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array. If the number of file descriptors is passed as 0, the call
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is fully equivalent to <function>sd_pid_notify()</function>, i.e.
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no file descriptors are passed. Note that sending file descriptors
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to the service manager on messages that do not expect them (i.e.
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without <literal>FDSTORE=1</literal>) they are immediately closed
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on reception.</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 <varname>$NOTIFY_SOCKET</varname> was not set and hence
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no status data could be sent, 0 is returned. If the status was
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sent, these functions return with a positive return value. In
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order to support both, init systems that implement this scheme and
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those which do not, it is generally recommended to ignore the
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return value of this call.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
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<para>Internally, these functions send a single datagram with the
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state string as payload to the <constant>AF_UNIX</constant> socket
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referenced in the <varname>$NOTIFY_SOCKET</varname> environment
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variable. If the first character of
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<varname>$NOTIFY_SOCKET</varname> is <literal>@</literal>, the
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string is understood as Linux abstract namespace socket. The
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datagram is accompanied by the process credentials of the sending
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service, using SCM_CREDENTIALS.</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist class='environment-variables'>
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<varlistentry>
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<term><varname>$NOTIFY_SOCKET</varname></term>
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<listitem><para>Set by the service manager for supervised
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processes for status and start-up completion notification.
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This environment variable specifies the socket
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<function>sd_notify()</function> talks to. 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>Examples</title>
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<example>
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<title>Start-up Notification</title>
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<para>When a service finished starting up, it might issue the
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following call to notify the service manager:</para>
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<programlisting>sd_notify(0, "READY=1");</programlisting>
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</example>
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<example>
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<title>Extended Start-up Notification</title>
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<para>A service could send the following after completing
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initialization:</para>
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<programlisting>sd_notifyf(0, "READY=1\n"
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"STATUS=Processing requests...\n"
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"MAINPID=%lu",
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(unsigned long) getpid());</programlisting>
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</example>
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<example>
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<title>Error Cause Notification</title>
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<para>A service could send the following shortly before exiting, on failure:</para>
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<programlisting>sd_notifyf(0, "STATUS=Failed to start up: %s\n"
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"ERRNO=%i",
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strerror(errno),
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errno);</programlisting>
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</example>
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<example>
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<title>Store a File Descriptor in the Service Manager</title>
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<para>To store an open file descriptor in the service manager,
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in order to continue operation after a service restart without
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losing state use <literal>FDSTORE=1</literal>:</para>
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<programlisting>sd_pid_notify_with_fds(0, 0, "FDSTORE=1", &fd, 1);</programlisting>
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</example>
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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_watchdog_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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