bash

find /[FOLDER_NAME]/* -mtime +[OLDER_THAN_DAYS] -exec rm -rf {} \;

Example deletes all files and folders in tmp folder that are older than 180 days: find /tmp/* -mtime +180 -exec rm -rf {} \;

In a lot of cases it is useful to convert bitmaps like jpg, png to vector graphics like SVG or AI.

Inkscape -> Path -> Trace Bitmap

BASH

convert file.png file.pnm
potrace file.pnm -s -o file.svg