Proc - TTY directory

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