I'm trying to learn more about X11. Omitting the hostname from the DISPLAY variable should imply the server is running locally, yes?
From a terminal running in Ubuntu:
$ echo $DISPLAY
Run 'xeyes' and the window pops up fine. But neither of the following work:
$ DISPLAY=localhost:0.0 xeyes
Error: Can't open display: localhost:0.0
$ DISPLAY=127.0.0.1:0.0 xeyes
Error: Can't open display: 127.0.0.1:0.0
Can someone elaborate on why this is?