I have installed 12.04 along with Windows 7 and also installed gnuplot 4.6.0. When I type gnuplot on the terminal, I am getting the error message: Terminal type set to unknown. When I tried plot sin(x), the graph does not appear on the screen. However, I am able to make a postscript file. I tried set terminal 'x11', system responds with: unknown or ambiguous terminal. Please help me solve this problem.