I've found a lovely set of SVG playing cards. The only problem is each image is displayed within a page. This means the relatively small cards have an enormous white margin.

Within Inkscape (the vector image editor for Linux) it's possible to crop the margins by going to:

"File → Document Properties → Resize Page To Content → Resize page to Drawing or Selection"

That's a pain in the arse for adjusting 52 images. Luckily, Inkscape will take command line arguments (called verbs⁰). This means we can point it to all SVG files in a directory, instruct it to Fit to Drawing, and save the file again.

It all takes place on one line.

inkscape --verb=FitCanvasToDrawing --verb=FileSave --verb=FileClose *.svg

Run that, the Inkscape window will pop up for each file, and automatically close once saved. I'm not sure if there's a way to do it on a headless install.