The tset command sets up your terminal when you first login to a UNIX system. It does terminal dependent processing such as setting erase and kill characters, setting delays, sending any sequences needed to properly initialize the terminal, and the like. It first determines the type of terminal and then does necessary initializations and mode settings.
Typically this kind of mode and environment initialization is done
once at login. The tset command , when no arguments are specified
simply reads the terminal type out of the environment variable TERM
and re-initialises the terminal. It is usually desirable to return the
terminal type, as finally determined by tset, and information about
the terminal's capabilities to a shell's environment. This can be done
using the - option with tset:
% setenv TERM 'tset - options'
The other options include -ec for setting the erase character to c; -kc for setting the kill character to c; etc..
Another useful terminal initialisation command, that uses tset, is reset. This is most useful after a program dies leaving a terminal in a funny state; you have to type <LF>reset<LF> to get it to work then to the shell, as <CR> often doesn't work; often none of this will echo. It would be a good idea to follow reset with tset.