NAME

       sd_bus_start - Initiate a bus connection to the D-bus broker daemon

SYNOPSIS

       #include <systemd/sd-bus.h>

       int sd_bus_start(sd_bus *bus);

DESCRIPTION

       sd_bus_start() connects an existing bus connection object to the D-Bus broker daemon,
       usually dbus-daemon(1) or dbus-broker(1). The mechanism to use for the connection must be
       configured before the call to sd_bus_start(), using one of sd_bus_set_address(3),
       sd_bus_set_fd(3), or sd_bus_set_exec(3).  sd_bus_start() will open the connection socket
       or spawn the executable as needed, and asynchronously start a org.freedesktop.DBus.Hello()
       call. The answer to the Hello call will be processed later from sd_bus_process(3). If
       opening of the connection or queuing of the asynchronous call fail, the connection will be
       closed with sd_bus_close(3).

       In most cases, it is better to use sd_bus_default_user(3), sd_bus_default_system(3) or
       related calls instead of the more low-level sd_bus_new() and sd_bus_start(). The
       higher-level functions not only allocate a bus object but also start the connection to a
       well-known bus in a single function call.

RETURN VALUE

       On success, this function returns a non-negative integer. On failure, it returns a
       negative errno-style error code.

   Errors
       -EINVAL
           The input parameter bus is NULL.

           Added in version 246.

       -ENOPKG
           Bus object bus could not be resolved.

           Added in version 246.

       -EPERM
           The input parameter bus is in a wrong state (sd_bus_start() may only be called once on
           a newly-created bus object).

           Added in version 246.

       -ECHILD
           The bus object bus was created in a different process.

           Added in version 246.

       In addition, other connection-related errors may be returned. See sd_bus_send(3).

NOTES

       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.

HISTORY

       sd_bus_start() was added in version 246.

SEE ALSO

       systemd(1), sd-bus(3), sd_bus_default(3), sd_bus_call_async(3)