systemd 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_process3 returns zero, indicating that no work is pending on the connection. Internally, this call invokes ppoll2, 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_fd3 or to an sd-event3 event loop using sd_bus_attach_event3. 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. 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. systemd1, sd-bus3, sd_bus_process3, sd_bus_get_fd3, sd-event3, sd_bus_attach_event3