Export images from Command Line


I’m trying to download osm map materiel as png from a java application. Till yesterday I thought it should be possible to just modify the link I get from the export tab on the homepage: http://tile.openstreetmap.org/cgi-bin/export?bbox=-12.6,42.0,12.4,59.4&scale=14000000&format=png and let the programm pass that to wget (a cli download manager in unix), but it doesn’t work. It seems like it’s only possible to download that way if you pushed the export button before. Does anybody know a way to do it like that or an other easy way to just download a .png image of x,y-x,y, maybe without using the whole osmerander engine?