The /etc/ttytype file associates termcap/terminfo terminal type names with tty lines. Each line consists of a terminal type, followed by whitespace, followed by a tty name (a device name without the /dev/") prefix."
This association is used by the program tset(1) to set the environment variable TERM to the default terminal name for the users current tty.
This facility was designed for a traditional time-sharing environment featuring character-cell terminals hardwired to a Unix minicomputer. It is little used on modern workstation and personal Unixes.
A typical /etc/ttytype is: