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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | NOTES | COLOPHON |
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SD_EVENT_RUN(3) sd_event_run SD_EVENT_RUN(3)
sd_event_run, sd_event_loop - Run an event loop
#include <systemd/sd-event.h>
int sd_event_run(sd_event *event, uint64_t usec);
int sd_event_loop(sd_event *event);
sd_event_run() may be used to run a single iteration of the event
loop specified in the event parameter. The function waits until an
event to process is available, and dispatches the registered
handler for it. The usec parameter specifies the maximum time (in
microseconds) to wait for an event. Use (uint64_t) -1 to specify
an infinite timeout.
sd_event_loop() invokes sd_event_run() in a loop, thus
implementing the actual event loop. The call returns as soon as
exiting was requested using sd_event_exit(3).
The event loop object event is created with sd_event_new(3).
Events sources to wait for and their handlers may be registered
with sd_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) and
sd_event_add_exit(3).
For low-level control of event loop execution, use
sd_event_prepare(3), sd_event_wait(3) and sd_event_dispatch(3)
which are wrapped by sd_event_run(). Along with
sd_event_get_fd(3), these functions allow integration of an
sd-event(3) event loop into foreign event loop implementations.
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 invoking sd_event_exit().
Errors
Returned errors may indicate the following problems:
-EINVAL
The event parameter is invalid or NULL.
-EBUSY
The event loop object is not in the right state (see
sd_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.
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.
sd_event_run() and sd_event_loop() were added in version 220.
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]
1. GLib Main Event Loop
https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html
This page is part of the systemd (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 is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SD_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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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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