# What does DISPLAY=:0.0 actually mean?

What does the :0.0 actually mean? I know that :0 is the first X server that is started on a local machine, :1 the second, etc. But what is that .0 part after :0? Do other combinations exist? (e.g. :0.0-something)

Background: I'm trying to improve the initscript of bumblebee which currently assumes that :0 is the active display. That is not the case if I switch users. So I wanted to validate the \$DISPLAY variable before passing it to vglclient.

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The format of the display variable is [host]:<display>[.screen].

host refers to a network host name, and if absent means to connect to the local machine via a unix domain socket.

Each host can have multiple displays, and each display can have multiple screens. Screens aren't used much anymore, with xinerama and now xrandr combining multiple screens into a single logical screen.

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Thanks, I just found the right manual page too, Xserver(1) referred to the DISPLAY NAMES section of X(7). Refer to that manual page for details. –  Lekensteyn Jul 17 '11 at 9:28
And how would I get a list of available displays for a certain host? Ideally within an ssh session where i'm logged in at the host from a client PC. –  con-f-use Aug 14 '12 at 11:59
@con-f-use That is a new question; you should create a new question rather than a comment. –  depquid Apr 17 '13 at 14:58