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sd_event_run(3) — Linux manual page

SD_EVENT_RUN(3)                sd_event_runSD_EVENT_RUN(3)

NAME        top

       sd_event_run, sd_event_loop - Run an event loop

SYNOPSIS        top

#include <systemd/sd-event.h>int sd_event_run(sd_event *event, uint64_tusec);int sd_event_loop(sd_event *event);

DESCRIPTION        top

sd_event_run()may be used to run a single iteration of the event       loop specified in theevent parameter. The function waits until an       event to process is available, and dispatches the registered       handler for it. Theusec parameter specifies the maximum time (in       microseconds) to wait for an event. Use(uint64_t) -1to specify       an infinite timeout.sd_event_loop()invokessd_event_run()in a loop, thus       implementing the actual event loop. The call returns as soon as       exiting was requested usingsd_event_exit(3).       The event loop objectevent is created withsd_event_new(3).       Events sources to wait for and their handlers may be registered       withsd_event_add_io(3),sd_event_add_time(3),sd_event_add_signal(3),sd_event_add_child(3),sd_event_add_defer(3),sd_event_add_post(3) andsd_event_add_exit(3).       For low-level control of event loop execution, usesd_event_prepare(3),sd_event_wait(3) andsd_event_dispatch(3)       which are wrapped bysd_event_run(). Along withsd_event_get_fd(3), these functions allow integration of ansd-event(3) event loop into foreign event loop implementations.

RETURN VALUE        top

       On failure, these functions return a negative errno-style error       code.sd_event_run()returns a positive, non-zero integer if an       event source was dispatched, and zero when the specified timeout       hit before an event source has seen any event, and hence no event       source was dispatched.sd_event_loop()returns the exit code       specified when invokingsd_event_exit().Errors       Returned errors may indicate the following problems:-EINVAL           Theevent parameter is invalid orNULL.-EBUSY           The event loop object is not in the right state (seesd_event_prepare(3) for an explanation of possible states).-ESTALE           The event loop is already terminated.-ECHILD           The event loop has been created in a different process,           library or module instance.       Other errors are possible, too.

NOTES        top

       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.

HISTORY        top

sd_event_run()andsd_event_loop()were added in version 220.

SEE ALSO        top

systemd(1),sd-event(3),sd_event_new(3),sd_event_add_io(3),sd_event_add_time(3),sd_event_add_signal(3),sd_event_add_child(3),sd_event_add_inotify(3),sd_event_add_defer(3),sd_event_exit(3),sd_event_get_fd(3),sd_event_wait(3),GLib Main Event Loop[1]

NOTES        top

        1. GLib Main Event Loophttps://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html

COLOPHON        top

       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_RUN(3)

Pages that refer to this page:sd-event(3), sd_event_exit(3), sd_event_new(3), sd_event_wait(3), systemd.directives(7), systemd.index(7)

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