The -s argument introduces the signature size. This is the number of sides which will be folder and bound together; this number should be a multiple of four. The default is to use one signature for the whole file.
Extra blank sides will be added to make the number of pages up to a multiple of the signature size.
If no output file is specified on the command line, the output is written to the standard output. If no input file is specified on the command line, the input is read from the standard input.
dvibook input.dvi output.dviIf the document is to be folded and stitched rather than guillotined and glued, the signature size should be restricted (or there may be too many pages to fold):
dvibook -s 16 input.dvi output.dvi