Makexvpics creates/updates xv/zgv/Gimp-compatible thumbnails for
picture files such as GIFs, JPEGs, etc. It may be useful if you want a
non-interactive way of keeping such files up to date.
The formats currently supported are GIF, JPEG, PNG, PBM/PGM/PPM, mrf,
BMP, TGA, and PCX.
OPTIONS
-f
force thumbnails to be updated. Ordinarily they're only updated if no
thumbnail exists or if the picture file is newer.
-h
give usage help.
-R
recurse into subdirectories.
-v
be verbose - echo names (or rather, `basename's) of files which are
being updated.