How to batch identify similar images in Linux

A Linux bash script to identify similar images, utilizing the imagemagick multi purpose image tool suite. The script scans for image files and compares all possible pairs within a set, calculating the Root Mean Square Error of image pixel values. Outputs a 3 column list: RMSE / source image / target image, sorted by RMSE. Similar images appear on the top of the list. You can redirect the output of the script to a text file for further processing, e.g. batch delete, import into libre office, etc.