Dear Maintainer,
The man page states that the output filename can be a dash or be
omitted, in which case the output goes to /dev/sdtout. Assuming the
documentation is correct, it's broken:
$ ddjvu -format=tiff myfile.djvu > /tmp/kmasdkfe.tiff
ddjvu: TIFF output requires a valid output file name.
$ ddjvu -format=tiff myfile.djvu - > /tmp/kmasdkfe.tiff
ddjvu: TIFF output requires a valid output file name.
If this is a deliberate limitation of TIFF files in particular, the
documentation should disclose the limitation.