Display command does not work

[Thomas_Tang]

To display the first mode shape, I wrote

...
eigen 1
set nEigen 1
set dAmp 10
display -$nEigen 0 $dAmp; # display mode shape for mode $nEigen
...

But I got the error message,"invalid command name "display", when running my script by OpenSees V1.7.5.

Is "display" no longer a OpenSees command?
Is it possible to view the mode shape without other software? Thanks!