Information about the available and actually used tty's can be found in the directory /proc/tty. You'll find entries for drivers and line disciplines in this directory, as shown in this Table.
| File | Content |
|---|---|
| drivers | List of drivers and their usage. |
| ldiscs | Registered line disciplines. |
| driver/serial | Usage statistic and status of single tty lines. |
To see which tty's are currently in use, you can simply look into the file /proc/tty/drivers:
cat /proc/tty/drivers pty_slave /dev/pts 136 0-255 pty:slave pty_master /dev/ptm 128 0-255 pty:master pty_slave /dev/ttyp 3 0-255 pty:slave pty_master /dev/pty 2 0-255 pty:master serial /dev/cua 5 64-67 serial:callout serial /dev/ttyS 4 64-67 serial /dev/tty0 /dev/tty0 4 0 system:vtmaster /dev/ptmx /dev/ptmx 5 2 system /dev/console /dev/console 5 1 system:console /dev/tty /dev/tty 5 0 system:/dev/tty unknown /dev/tty 4 1-63 console