xdvi filename &
creates a window which shows you what the file
will look like when it is printed on the printer. After you position
the xdvi
window on your screen, it should show the first page
of the document. You can use this like the more
command: hit
space to go forward a page, and b
to go back a page. This way
you can go back and forth between the xdvi
previewer and the
LATEX source, rerunning LATEX and looking at the xdvi
display each time. (xdvi
automatically notices that you've
changed something, and displays the newest output.)