sd-daemon

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## 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` provide APIs for new-style daemons, as implemented by the systemd(1) init system.

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=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), sd-readahead(3), pkg-config(1)