SD-DAEMON(3)                       sd-daemon                      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 is part of libsystemd(3) and 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 (or stdout-based logging) as implemented by systemd. If a
       systemd service definition file is configured with
       StandardError=journal or StandardError=kmsg (and similar with
       StandardOutput=), 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
       Functions described here are available as a shared library, which can
       be compiled against and linked to with the libsystemd pkg-config(1)
       file.

       The code described here uses getenv(3), which is declared to be not
       multi-thread-safe. This means that the code calling the functions
       described here must not call setenv(3) from a parallel thread. It is
       recommended to only do calls to setenv() from an early phase of the
       program when no other threads have been started.

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)

systemd 255                                                       SD-DAEMON(3)