Manpages - sd-daemon.3

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

  #include <systemd/sd-daemon.h>

pkg-config –cflags –libs libsystemd

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 (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");

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

*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)