man/sd-daemon.xml

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   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
  26         <refentryinfo>
  27                 <title>sd-daemon</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd-daemon</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd-daemon</refname>
  47                 <refname>SD_EMERG</refname>
  48                 <refname>SD_ALERT</refname>
  49                 <refname>SD_CRIT</refname>
  50                 <refname>SD_ERR</refname>
  51                 <refname>SD_WARNING</refname>
  52                 <refname>SD_NOTICE</refname>
  53                 <refname>SD_INFO</refname>
  54                 <refname>SD_DEBUG</refname>
  55                 <refpurpose>APIs for
  56                 new-style daemons</refpurpose>
  57         </refnamediv>
  58
  59         <refsynopsisdiv>
  60                 <funcsynopsis>
  61                         <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  62                 </funcsynopsis>
  63
  64                 <cmdsynopsis>
  65                         <command>pkg-config --cflags --libs libsystemd</command>
  66                 </cmdsynopsis>
  67
  68         </refsynopsisdiv>
  69
  70         <refsect1>
  71                 <title>Description</title>
  72
  73                 <para><filename>sd-daemon.h</filename> provide APIs
  74                 for new-style daemons, as implemented by the
  75                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  76                 init system.</para>
  77
  78                 <para>See
  79                 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  80                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  81                 <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  82                 <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  83                 <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  84                 for more information about the functions
  85                 implemented. In addition to these functions, a couple
  86                 of logging prefixes are defined as macros:</para>
  87
  88                 <programlisting>#define SD_EMERG   "&lt;0&gt;"  /* system is unusable */
  89 #define SD_ALERT   "&lt;1&gt;"  /* action must be taken immediately */
  90 #define SD_CRIT    "&lt;2&gt;"  /* critical conditions */
  91 #define SD_ERR     "&lt;3&gt;"  /* error conditions */
  92 #define SD_WARNING "&lt;4&gt;"  /* warning conditions */
  93 #define SD_NOTICE  "&lt;5&gt;"  /* normal but significant condition */
  94 #define SD_INFO    "&lt;6&gt;"  /* informational */
  95 #define SD_DEBUG   "&lt;7&gt;"  /* debug-level messages */</programlisting>
  96
  97                 <para>These prefixes are intended to be used in
  98                 conjunction with stderr-based logging as implemented
  99                 by systemd. If a systemd service definition file is
 100                 configured with <varname>StandardError=syslog</varname>
 101                 or <varname>StandardError=kmsg</varname>, these
 102                 prefixes can be used to encode a log level in lines
 103                 printed. This is similar to the kernel
 104                 <function>printk()</function>-style logging. See
 105                 <citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 106                 for more information.</para>
 107
 108                 <para>The log levels are identical to
 109                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
 110                 log level system. To use these prefixes simply prefix
 111                 every line with one of these strings. A line that is
 112                 not prefixed will be logged at the default log level
 113                 SD_INFO.</para>
 114
 115                 <example>
 116                         <title>Hello World</title>
 117
 118                         <para>A daemon may log with the log level
 119                         NOTICE by issuing this call:</para>
 120
 121                         <programlisting>fprintf(stderr, SD_NOTICE "Hello World!\n");</programlisting>
 122                 </example>
 123         </refsect1>
 124
 125         <refsect1>
 126                 <title>Notes</title>
 127
 128                 <para>These APIs are implemented as a shared library,
 129                 which can be compiled and linked to with the
 130                 <constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 131                 file.</para>
 132         </refsect1>
 133
 134         <refsect1>
 135                 <title>See Also</title>
 136                 <para>
 137                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 138                         <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 139                         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 140                         <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 141                         <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 142                         <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 143                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 144                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 145                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 146                         <citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 147                         <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 148                         <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 149                 </para>
 150         </refsect1>
 151
 152 </refentry>