man/sd-daemon.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="sd-daemon"
  25   xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>sd-daemon</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>sd-daemon</refentrytitle>
  43     <manvolnum>3</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>sd-daemon</refname>
  48     <refname>SD_EMERG</refname>
  49     <refname>SD_ALERT</refname>
  50     <refname>SD_CRIT</refname>
  51     <refname>SD_ERR</refname>
  52     <refname>SD_WARNING</refname>
  53     <refname>SD_NOTICE</refname>
  54     <refname>SD_INFO</refname>
  55     <refname>SD_DEBUG</refname>
  56     <refpurpose>APIs for
  57     new-style daemons</refpurpose>
  58   </refnamediv>
  59
  60   <refsynopsisdiv>
  61     <funcsynopsis>
  62       <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  63     </funcsynopsis>
  64
  65     <cmdsynopsis>
  66       <command>pkg-config --cflags --libs libsystemd</command>
  67     </cmdsynopsis>
  68
  69   </refsynopsisdiv>
  70
  71   <refsect1>
  72     <title>Description</title>
  73
  74     <para><filename>sd-daemon.h</filename> provide APIs for new-style
  75     daemons, as implemented by the
  76     <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  77     init system.</para>
  78
  79     <para>See
  80     <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  81     <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  82     <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  83     <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  84     <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  85     for more information about the functions implemented. In addition
  86     to these functions, a couple of logging prefixes are defined as
  87     macros:</para>
  88
  89     <programlisting>#define SD_EMERG   "&lt;0&gt;"  /* system is unusable */
  90 #define SD_ALERT   "&lt;1&gt;"  /* action must be taken immediately */
  91 #define SD_CRIT    "&lt;2&gt;"  /* critical conditions */
  92 #define SD_ERR     "&lt;3&gt;"  /* error conditions */
  93 #define SD_WARNING "&lt;4&gt;"  /* warning conditions */
  94 #define SD_NOTICE  "&lt;5&gt;"  /* normal but significant condition */
  95 #define SD_INFO    "&lt;6&gt;"  /* informational */
  96 #define SD_DEBUG   "&lt;7&gt;"  /* debug-level messages */</programlisting>
  97
  98     <para>These prefixes are intended to be used in conjunction with
  99     stderr-based logging as implemented by systemd. If a systemd
 100     service definition file is configured with
 101     <varname>StandardError=journal</varname>,
 102     <varname>StandardError=syslog</varname> or
 103     <varname>StandardError=kmsg</varname>, these prefixes can be used
 104     to encode a log level in lines printed. This is similar to the
 105     kernel <function>printk()</function>-style logging. See
 106     <citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 107     for more information.</para>
 108
 109     <para>The log levels are identical to
 110     <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
 111     log level system. To use these prefixes simply prefix every line
 112     with one of these strings. A line that is not prefixed will be
 113     logged at the default log level SD_INFO.</para>
 114
 115     <example>
 116       <title>Hello World</title>
 117
 118       <para>A daemon may log with the log level NOTICE by issuing this
 119       call:</para>
 120
 121       <programlisting>fprintf(stderr, SD_NOTICE "Hello World!\n");</programlisting>
 122     </example>
 123   </refsect1>
 124
 125   <xi:include href="libsystemd-pkgconfig.xml" />
 126
 127   <refsect1>
 128     <title>See Also</title>
 129     <para>
 130       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 131       <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 132       <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 133       <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 134       <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 135       <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 136       <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 137       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 138       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 139       <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 140       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 141     </para>
 142   </refsect1>
 143
 144 </refentry>