By default, the number of pseudo-ttys is 48. The user can define as many pseudo ttys as required by him. More than 3000 pseudo ttys are supported by the system. The pseudo ttys are not associated to any physical hardware. They are used to simulate the functioning of a real tty. A user can add pseudo ttys by editing the /etc/system and adding the following lines

* System V pseudo terminals
set pt_cnt =
Halt the system and boot -r
The pseudo tty is created using the mkdev ptty command

A user should not add unnecessary pseudo ttys as they just waste memory space. A pseudo-tty can be used for various purposes, a good example of its usage is in the networking domain, the pseudo ttys are used to login to a remote device. The pseudo tty is represented by two software devices which appear in form of a listing of /dev as the ptyp and ttyp. The ttyp is considered to be the master and the ptyp is considered to be a slave.   _{Your Comment}