System Administration Guide
Appendix B, Using the system console and non-graphical displays

Adding pseudo-ttys

Adding pseudo-ttys

A pseudo-tty is a device that is not associated with any real hardware, and it is used to simulate the function of a real tty. Users of networking products should already be familiar with pseudo-ttys, as they are the devices used to log in on remote machines. A pseudo-tty is represented by two software devices that appear in a listing of /dev as ptyp and ttyp, each followed by a number. The former is called the ``master'' tty and the latter the ``slave''. Between the two, they simulate a functional tty. 

Pseudo-ttys are created with the mkdev ptty command.

To configure the pseudo-ttys, log in as root and enter the following command:

mkdev ptty

This automatically creates the necessary devices, updates the files /etc/inittab and /etc/conf/cf.d/init.base, and updates the NSPTTYS kernel parameter (the maximum number of pseudo-ttys) as necessary. If this value is increased, a kernel relink will be necessary.