systemd sd_bus_start 3 sd_bus_start Initiate a bus connection to the D-bus broker daemon #include <systemd/sd-bus.h> int sd_bus_start sd_bus *bus sd_bus_start() connects an existing bus connection object to the D-Bus broker daemon, usually dbus-daemon1 or dbus-broker1. The mechanism to use for the connection must be configured before the call to sd_bus_start(), using one of sd_bus_set_address3, sd_bus_set_fd3, or sd_bus_set_exec3. 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_process3. If opening of the connection or queuing of the asynchronous call fail, the connection will be closed with sd_bus_close3. In most cases, it is better to use sd_bus_default_user3, sd_bus_default_system3 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. On success, this function returns a non-negative integer. On failure, it returns a negative errno-style error code. -EINVAL The input parameter bus is NULL. -ENOPKG Bus object bus could not be resolved. -EPERM The input parameter bus is in a wrong state (sd_bus_start() may only be called once on a newly-created bus object). -ECHILD The bus object bus was created in a different process. In addition, other connection-related errors may be returned. See sd_bus_send3. systemd1, sd-bus3, sd_bus_default3, sd_bus_call_async3