Referencing this post I have successfully managed to get a Linux Device (A Raspberry Pi Model A+) to switch my Bluetooth 4.0 USB dongle into the 'advertising' state:
sudo hciconfig hci0 leadv 3
sudo hciconfig hci0 leadv 0
sudo hcitool lescan --passive
LE Scan ...
There is no argument in hcitool for that, however here are some options
timeout 15s hcitool lescanThis will run the scan for 15s
hcitool lescan --duplicatesThis will report each device only once
(unknown): I assume your peripheral does not include the Bluetooth name in the advertising or even not at all.
--passive tells your HCI Device to not request the ScanResponse (which probably contains the name), thus the name remains unknown, whereas the iOS APIs do an active scan and receive the name.