How can I specify a display?

Question

When I run some programs over SSH, such as firefox &, I get an error

Error: no display specified 

I would like to open ma

Answer 1

I through vnc to understand the X11 more. To specify the display to get a many-displayed program, export DISPLAY=IP:DisplayNum.ScreenNum

For example,

vncserver :2
vncserver -list
echo '$DISPLAY'=$DISPLAY 
export DISPLAY=:2  # export DISPLAY=IP:DisplayNum or export DISPLAY=:DisplayNum for localhost; So that can vnc connect and see the vnc desktop :2 if $DISPLAY is not :2.
echo '$DISPLAY'=$DISPLAY