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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_ATTACH_EVENT(3) sd_bus_attach_event SD_BUS_ATTACH_EVENT(3)
sd_bus_attach_event, sd_bus_detach_event, sd_bus_get_event -
Attach a bus connection object to an event loop
#include <systemd/sd-bus.h>
int sd_bus_attach_event(sd_bus *bus, sd_event *e, int priority);
int sd_bus_detach_event(sd_bus *bus);
sd_event *sd_bus_get_event(sd_bus *bus);
sd_bus_attach_event() attaches the specified bus connection object
to an sd-event(3) event loop object at the specified priority (see
sd_event_source_set_priority(3) for details on event loop
priorities). When a bus connection object is attached to an event
loop incoming messages will be automatically read and processed,
and outgoing messages written, whenever the event loop is run.
When the event loop is about to terminate, the bus connection is
automatically flushed and closed (see sd_bus_set_close_on_exit(3)
for details on this). By default, bus connection objects are not
attached to any event loop. When a bus connection object is
attached to one it is not necessary to invoke sd_bus_wait(3) or
sd_bus_process(3) as this functionality is handled automatically
by the event loop.
sd_bus_detach_event() detaches a bus object from its event loop.
The sd_bus_get_event() returns the event loop object the specified
bus object is currently attached to, or NULL if it is currently
not attached to any.
Note that sd_bus_attach_event() is only one of three supported
ways to implement I/O event handling for bus connections.
Alternatively use sd_bus_get_fd(3) for hooking up a bus connection
object with external or manual event loops. Or use sd_bus_wait(3)
as a simple synchronous, blocking I/O waiting call.
On success, sd_bus_attach_event() and sd_bus_detach_event() return
0 or a positive integer. On failure, they return a negative
errno-style error code.
sd_bus_get_event() returns an event loop object or NULL.
Errors
Returned errors may indicate the following problems:
-ECHILD
The bus connection has been 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 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_bus_attach_event(), sd_bus_detach_event(), and
sd_bus_get_event() were added in version 221.
systemd(1), sd-bus(3), sd-event(3),
sd_event_source_set_priority(3), sd_bus_set_close_on_exit(3),
sd_bus_wait(3), sd_bus_get_fd(3)
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
[email protected]
systemd 258~rc2 SD_BUS_ATTACH_EVENT(3)
Pages that refer to this page: sd-bus(3), sd_bus_get_fd(3), sd_bus_process(3), sd_bus_set_close_on_exit(3), sd_bus_set_exit_on_disconnect(3), sd_bus_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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