Syntax:
     set terminal {<terminal-type> | push | pop}
     show terminal
If terminal-type
 is omitted, gnuplot will list the available terminal
types.  
terminal-type
 may be abbreviated.
If both set terminal and set output are used together, it is safest to give set terminal first, because some terminals set a flag which is needed in some operating systems.
Some terminals have many additional options.
The options used by a previous invocation set term term
 
options
 of a
given 
term
 are remembered, thus subsequent set term 
term
 does
not reset them.  This helps in printing, for instance, when switching
among different terminals — previous options don't have to be repeated.
The command set term push remembers the current terminal including its settings while set term pop restores it. This is equivalent to save term and load term, but without accessing the filesystem. Therefore they can be used to achieve platform independent restoring of the terminal after printing, for instance. After gnuplot's startup, the default terminal or that from startup file is pushed automatically. Therefore portable scripts can rely that set term pop restores the default terminal on a given platform unless another terminal has been pushed explicitly.
For more information, see the complete list of terminals (p. 
).