man/sd-daemon.xml

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