Oneliner

(as root) This could be a long list, so you might want to redirect the output into a file for perusal...

find / -xdev -type f -size +10000k -mtime -3 -ls | sort -n -k 7,7
	

Log in as root and execute crontab -e, add a line like this:

0 1  * * *  find / -name '*~' -exec rm {} \;

This command will execute everyday at 1 o'clock in the morning and remove all files that end with a ~. If you want to delete core files, replace *~ with core above.

man mmv assuming that you have mmv installed on your system. Your example would be:

mmv "IMG_*.JPG" "Disneyland_#1.JPG"
	    

You could also use

mmv "IMG_*.*" "Disneyland_#1.#2"
	    

if you had a mix of .JPG and .jpg images that you wanted to rename at once.