upscli_fd (3) - Linux Manuals
upscli_fd: Get file descriptor for connection
upscli_fd - Get file descriptor for connection
int upscli_fd(UPSCONN_t *ups);
The upscli_fd() function takes the pointer ups to a UPSCONN_t state structure and returns the value of the file descriptor for that connection, if any.
This may be useful for determining if the connection to upsd(8) has been lost.