systemd sd_bus_set_fd 3 sd_bus_set_fd Set the file descriptors to use for bus communication #include <systemd/sd-bus.h> int sd_bus_set_fd sd_bus *bus int input_fd int output_fd sd_bus_set_fd() sets the file descriptors used to communicate by a bus connection object. Both input_fd and output_fd must be valid file descriptors, referring to stream-based file objects (e.g. a stream socket, a pair of pipes or FIFOs, or even a TTY device). input_fd must be readable, and output_fd must be writable. The same file descriptor may be used (and typically is used) as both the input and the output file descriptor. This function must be called before the bus connection is started via sd_bus_start3. The bus connection object will take possession of the passed file descriptors and will close them automatically when it is freed. Use sd_bus_set_close_on_exit3 to turn off this behaviour. On success, sd_bus_set_fd() returns a non-negative integer. On failure, it returns a negative errno-style error code. 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(). -EBADF An invalid file descriptor was passed to sd_bus_set_fd(). -ENOPKG The bus cannot be resolved. -EPERM The bus connection has already been started. sd_bus_set_fd() was added in version 248. systemd1, sd-bus3, sd_bus_get_fd3, sd_bus_start3