sd-daemon(3)

NAME

   sd-daemon, SD_EMERG, SD_ALERT, SD_CRIT, SD_ERR, SD_WARNING, SD_NOTICE,
   SD_INFO, SD_DEBUG - APIs for new-style daemons

SYNOPSIS

   #include <systemd/sd-daemon.h>

   pkg-config --cflags --libs libsystemd

DESCRIPTION

   sd-daemon.h provides APIs for new-style daemons, as implemented by the
   systemd(1) service manager.

   See sd_listen_fds(3), sd_notify(3), sd_booted(3), sd_is_fifo(3),
   sd_watchdog_enabled(3) for more information about the functions
   implemented. In addition to these functions, a couple of logging
   prefixes are defined as macros:

       #define SD_EMERG   "<0>"  /* system is unusable */
       #define SD_ALERT   "<1>"  /* action must be taken immediately */
       #define SD_CRIT    "<2>"  /* critical conditions */
       #define SD_ERR     "<3>"  /* error conditions */
       #define SD_WARNING "<4>"  /* warning conditions */
       #define SD_NOTICE  "<5>"  /* normal but significant condition */
       #define SD_INFO    "<6>"  /* informational */
       #define SD_DEBUG   "<7>"  /* debug-level messages */

   These prefixes are intended to be used in conjunction with stderr-based
   logging as implemented by systemd. If a systemd service definition file
   is configured with StandardError=journal, StandardError=syslog or
   StandardError=kmsg, these prefixes can be used to encode a log level in
   lines printed. This is similar to the kernel printk()-style logging.
   See klogctl(2) for more information.

   The log levels are identical to syslog(3)'s log level system. To use
   these prefixes simply prefix every line with one of these strings. A
   line that is not prefixed will be logged at the default log level
   SD_INFO.

   Example 1. Hello World

   A daemon may log with the log level NOTICE by issuing this call:

       fprintf(stderr, SD_NOTICE "Hello World!\n");

NOTES

   These APIs are implemented as a shared library, which can be compiled
   and linked to with the libsystemd pkg-config(1) file.

SEE ALSO

   systemd(1), sd_listen_fds(3), sd_notify(3), sd_booted(3),
   sd_is_fifo(3), sd_watchdog_enabled(3), daemon(7), systemd.service(5),
   systemd.socket(5), fprintf(3), pkg-config(1)

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