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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |COLOPHON | |
SD_EVENT_NOW(3) sd_event_nowSD_EVENT_NOW(3)sd_event_now - Retrieve current event loop iteration timestamp
#include <systemd/sd-event.h>int sd_event_now(sd_event *event, clockid_tclock, uint64_t *ret);
sd_event_now()returns the time when the most recent event loop iteration began. A timestamp is taken right after returning from the event sleep, and before dispatching any event sources. Theevent parameter specifies the event loop object to retrieve the timestamp from. Theclock parameter specifies the clock to retrieve the timestamp for, and is one ofCLOCK_REALTIME(or equivalentlyCLOCK_REALTIME_ALARM),CLOCK_MONOTONIC, orCLOCK_BOOTTIME(or equivalentlyCLOCK_BOOTTIME_ALARM), seeclock_gettime(2) for more information on the various clocks. The retrieved timestamp is stored in theret parameter, in μs since the clock's epoch. If this function is invoked before the first event loop iteration, the current time is returned, as reported byclock_gettime(). To distinguish this case from a regular invocation the return value will be positive, and zero when the returned timestamp refers to an actual event loop iteration.
If the first event loop iteration has not run yetsd_event_now() writes current time toret and returns a positive return value. Otherwise, it will write the requested timestamp toret and return 0. On failure, the call returns a negative errno-style error code.Errors Returned values may indicate the following problems:-EINVAL An invalid parameter was passed.-EOPNOTSUPP Unsupported clock type.-ECHILD The event loop object was created in a different process, library or module instance.
Functions described here are available as a shared library, which can be compiled against and linked to with thelibsystemd pkg-config(1) file. The code described here usesgetenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not callsetenv(3) from a parallel thread. It is recommended to only do calls tosetenv()from an early phase of the program when no other threads have been started.
sd_event_now()was added in version 229.
systemd(1),sd-event(3),sd_event_new(3),sd_event_add_time(3),clock_gettime(2)
This page is part of thesystemd (systemd system and service manager) project. Information about the project can be found at ⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug report for this manual page, see ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This page was obtained from the project's upstream Git repository ⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgsystemd 258~rc2SD_EVENT_NOW(3)Pages that refer to this page:sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_signal(3), sd_event_add_time(3), systemd.directives(7), systemd.index(7)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |