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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_WAIT(3) sd_bus_wait SD_BUS_WAIT(3)
sd_bus_wait - Wait for I/O on a bus connection
#include <systemd/sd-bus.h>
int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec);
sd_bus_wait() synchronously waits for I/O on the specified bus
connection object. This function is supposed to be called whenever
sd_bus_process(3) returns zero, indicating that no work is pending
on the connection. Internally, this call invokes ppoll(2), to wait
for I/O on the bus connection. If the timeout_usec parameter is
specified, the call will block at most for the specified amount of
time in μs. Pass UINT64_MAX to permit it to sleep indefinitely.
After each invocation of sd_bus_wait() the sd_bus_process() call
should be invoked in order to process any now pending I/O work.
Note that sd_bus_wait() is suitable only for simple programs as it
does not permit waiting for other I/O events. For more complex
programs either connect the bus connection object to an external
event loop using sd_bus_get_fd(3) or to an sd-event(3) event loop
using sd_bus_attach_event(3).
If any I/O was seen, a positive value is returned, zero otherwise.
If an error occurs, a negative errno-style error code is returned.
Errors
Returned errors may indicate the following problems:
-EINVAL
An invalid bus object was passed.
-ECHILD
The bus connection was allocated in a parent process and is
being reused in a child process after fork().
-ENOTCONN
The bus connection has been terminated already.
Functions described here are available as a shared library, which
can be compiled against and linked to with the
libsystemd pkg-config(1) file.
All functions listed here are thread-agnostic and only a single
thread may operate on a given object at any given time. Different
threads may access the same object at different times. Multiple
independent objects may be used from different threads in
parallel.
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_wait() was added in version 240.
systemd(1), sd-bus(3), sd_bus_process(3), sd_bus_get_fd(3),
sd-event(3), sd_bus_attach_event(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 2026-08-04. (At that
time, the date of the most recent commit that was found in the
repository was 2026-08-03.) 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 262~devel SD_BUS_WAIT(3)
Pages that refer to this page: sd-bus(3), sd_bus_attach_event(3), sd_bus_get_fd(3), sd_bus_process(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2026-09-09 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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