3.1 Unix Display Names

A display name on Unix has the following syntax:

[hostname]:displayno[.screenno]

If hostname is omitted this refers to a display on the same machine as the client is running on. A Unix socket is used to connect to the display identified by displayno, which must be an integer from 0 and upwards.

If hostname is specified, it gives the network name or IP-number of the machine to contact. A TCP socket is used, connecting to port 6000+displayno on hostname.

If the display contains more than one screen, screenno can be specified to make another screen than 0 the default screen. If the number is larger than the available maximum screen number, it will be set to the maximum.

A few examples:

:0           Display 0 on this host, connects to the Unix socket
             /tmp/.X11-unix/X0
:0.1         Same as above, but specifying a different default screen

myhost:0     Display 0 on myhost, connects to TCP port 6000
myhost:10    Display 10 on myhost, connects to TCP port 6010

localhost:0  Display 0 on localhost, i.e. the same host as the client
             runs on.  Uses a TCP socket, while :0 uses a Unix socket

The default display name is stored in the environmental variable DISPLAY. If that isn’t set, error.DisplayNameError is raised.

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