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
  75                 for new-style 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
  86                 implemented. In addition to these functions, a couple
  87                 of logging prefixes are defined as 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
  99                 conjunction with stderr-based logging as implemented
 100                 by systemd. If a systemd service definition file is
 101                 configured with
 102                 <varname>StandardError=journal</varname>,
 103                 <varname>StandardError=syslog</varname> or
 104                 <varname>StandardError=kmsg</varname>, these prefixes
 105                 can be used to encode a log level in lines
 106                 printed. This is similar to the kernel
 107                 <function>printk()</function>-style logging. See
 108                 <citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 109                 for more information.</para>
 110
 111                 <para>The log levels are identical to
 112                 <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
 113                 log level system. To use these prefixes simply prefix
 114                 every line with one of these strings. A line that is
 115                 not prefixed will be logged at the default log level
 116                 SD_INFO.</para>
 117
 118                 <example>
 119                         <title>Hello World</title>
 120
 121                         <para>A daemon may log with the log level
 122                         NOTICE by issuing this call:</para>
 123
 124                         <programlisting>fprintf(stderr, SD_NOTICE "Hello World!\n");</programlisting>
 125                 </example>
 126         </refsect1>
 127
 128         <xi:include href="libsystemd-pkgconfig.xml" />
 129
 130         <refsect1>
 131                 <title>See Also</title>
 132                 <para>
 133                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 134                         <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 135                         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 136                         <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 137                         <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 138                         <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 139                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 140                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 141                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 142                         <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 143                         <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 144                 </para>
 145         </refsect1>
 146
 147 </refentry>