1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"sd-daemon"
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>sd-daemon
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>sd-daemon
</refentrytitle>
16 <manvolnum>3</manvolnum>
20 <refname>sd-daemon
</refname>
21 <refname>SD_EMERG
</refname>
22 <refname>SD_ALERT
</refname>
23 <refname>SD_CRIT
</refname>
24 <refname>SD_ERR
</refname>
25 <refname>SD_WARNING
</refname>
26 <refname>SD_NOTICE
</refname>
27 <refname>SD_INFO
</refname>
28 <refname>SD_DEBUG
</refname>
30 new-style daemons
</refpurpose>
35 <funcsynopsisinfo>#include
<systemd/sd-daemon.h
></funcsynopsisinfo>
39 <command>pkg-config --cflags --libs libsystemd
</command>
45 <title>Description
</title>
47 <para><filename>sd-daemon.h
</filename> provides APIs for new-style
48 daemons, as implemented by the
49 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
50 service manager.
</para>
53 <citerefentry><refentrytitle>sd_listen_fds
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
54 <citerefentry><refentrytitle>sd_notify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
55 <citerefentry><refentrytitle>sd_booted
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
56 <citerefentry><refentrytitle>sd_is_fifo
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
57 <citerefentry><refentrytitle>sd_watchdog_enabled
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
58 for more information about the functions implemented. In addition
59 to these functions, a couple of logging prefixes are defined as
62 <programlisting>#define SD_EMERG
"<0>" /* system is unusable */
63 #define SD_ALERT
"<1>" /* action must be taken immediately */
64 #define SD_CRIT
"<2>" /* critical conditions */
65 #define SD_ERR
"<3>" /* error conditions */
66 #define SD_WARNING
"<4>" /* warning conditions */
67 #define SD_NOTICE
"<5>" /* normal but significant condition */
68 #define SD_INFO
"<6>" /* informational */
69 #define SD_DEBUG
"<7>" /* debug-level messages */
</programlisting>
71 <para>These prefixes are intended to be used in conjunction with stderr-based logging (or stdout-based
72 logging) as implemented by systemd. If a systemd service definition file is configured with
73 <varname>StandardError=journal
</varname> or
<varname>StandardError=kmsg
</varname> (and similar with
74 <varname>StandardOutput=
</varname>), these prefixes can be used to encode a log level in lines
75 printed. This is similar to the kernel
<function>printk()
</function>-style logging. See
76 <citerefentry><refentrytitle>klogctl
</refentrytitle><manvolnum>2</manvolnum></citerefentry> for more
79 <para>The log levels are identical to
80 <citerefentry project='man-pages'
><refentrytitle>syslog
</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
81 log level system. To use these prefixes simply prefix every line
82 with one of these strings. A line that is not prefixed will be
83 logged at the default log level SD_INFO.
</para>
86 <title>Hello World
</title>
88 <para>A daemon may log with the log level NOTICE by issuing this
91 <programlisting>fprintf(stderr, SD_NOTICE
"Hello World!\n");
</programlisting>
95 <xi:include href=
"libsystemd-pkgconfig.xml" />
98 <title>See Also
</title>
100 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
101 <citerefentry><refentrytitle>sd_listen_fds
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
102 <citerefentry><refentrytitle>sd_notify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
103 <citerefentry><refentrytitle>sd_booted
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
104 <citerefentry><refentrytitle>sd_is_fifo
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
105 <citerefentry><refentrytitle>sd_watchdog_enabled
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
106 <citerefentry><refentrytitle>daemon
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
107 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
108 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
109 <citerefentry project='man-pages'
><refentrytitle>fprintf
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
110 <citerefentry project='die-net'
><refentrytitle>pkg-config
</refentrytitle><manvolnum>1</manvolnum></citerefentry>