sd_bus_close(3) — Linux manual page


SD_BUS_CLOSE(3)               sd_bus_close               SD_BUS_CLOSE(3)

NAME         top

       sd_bus_close, sd_bus_flush, sd_bus_default_flush_close - Close
       and flush a bus connection

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       void sd_bus_close(sd_bus *bus);

       int sd_bus_flush(sd_bus *bus);

       void sd_bus_default_flush_close(void);

DESCRIPTION         top

       sd_bus_close() disconnects the specified bus connection. When
       this call is invoked and the specified bus object refers to an
       active connection it is immediately terminated. No further
       messages may be sent or received on it. Any messages queued in
       the bus object (both incoming and outgoing) are released. If
       invoked on NULL bus object or when the bus connection is already
       closed this function executes no operation. This call does not
       free or unreference the bus object itself. Use sd_bus_unref(3)
       for that.

       sd_bus_flush() synchronously writes out all outgoing queued
       message on a bus connection if there are any. This function call
       may block if the peer is not processing bus messages quickly.

       Before a program exits it is usually a good idea to flush any
       pending messages with sd_bus_flush() and then close connections
       with sd_bus_close() to ensure that no unwritten messages are
       lost, no further messages may be queued and all incoming but
       unprocessed messages are released. After both operations have
       been done, it is a good idea to also drop any remaining
       references to the bus object so that it may be freed. Since these
       three operations are frequently done together a helper call
       sd_bus_flush_close_unref(3) is provided that combines them into

       sd_bus_default_flush_close() is similar to
       sd_bus_flush_close_unref(), but does not take a bus pointer
       argument and instead iterates over any of the "default" buses
       opened by sd_bus_default(3), sd_bus_default_user(3),
       sd_bus_default_system(3), and similar calls.
       sd_bus_default_flush_close() is particularly useful to clean up
       any buses opened using those calls before the program exits.

RETURN VALUE         top

       On success, sd_bus_flush() returns a non-negative integer. On
       failure, it returns a negative errno-style error code.

       Returned errors may indicate the following problems:

           The bus connection has been created in a different process,
           library or module instance.

NOTES         top

       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

HISTORY         top

       sd_bus_close() and sd_bus_flush() were added in version 221.

       sd_bus_default_flush_close() was added in version 227.

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_unref(3),

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-13.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

systemd 257~devel                                        SD_BUS_CLOSE(3)

Pages that refer to this page: sd-bus(3)sd_bus_default(3)sd_bus_get_n_queued_read(3)sd_bus_is_open(3)sd_bus_new(3)sd_bus_set_close_on_exit(3)sd_bus_start(3)systemd.directives(7)systemd.index(7)