Batch resize images on Ubuntu

Found this thread on how to batch resize images:
http://ubuntuforums.org/showthread.php?t=170862

For horizontal conversion:

for i in `ls`; do convert -resize 1600 $i hresized_$i; done

For vertical conversion:

for i in `ls`; do convert -resize x1200 $i vresized_$i; done

Just make sure that the target file name is different, otherwise you'll end up with a bunch of corrupted images because imagemagick will overwrite your image without checking. It would be cool if it would automatically create a tmp file and after it is finished, overwrite the original. But hey, at least we won't have to do it one by one using Gimp.