SD-DAEMON(3)

  .SH "NAME" sd-daemon, SD_EMERG, SD_ALERT, SD_CRIT, SD_ERR, SD_WARNING, SD_NOTICE, SD_INFO, SD_DEBUG - APIs for new-style daemons
  .SH "SYNOPSIS"

#include <systemd/sd-daemon.h>

    .HP u
      pkg-config --cflags --libs libsystemd

  .SH "DESCRIPTION"

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

    .PP 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.
    .PP 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.
    .PP Example 1. Hello World

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

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

  .SH "NOTES"

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

    .PP 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)