square image bash

gistfile1.txt

#!/bin/bash
for FILE in $(ls *.jpg)
do
	W=`identify -verbose "$FILE" | grep -oe "Geometry:.*" | sed -e 's/.*: //' | sed -e 's/x.*//'`
	H=`identify -verbose "$FILE" | grep -oe "Geometry:.*" | sed -e 's/.*x//' | sed -e 's/+.*//'`
	if [ "$W" -gt "$H" ]
	then
		mogrify "$FILE" -extent "$W"x"$W" -gravity center -quality 100 jpeg:"$FILE"
	fi
	if [ "$H" -gt "$W" ]
	then
		mogrify "$FILE" -extent "$H"x"$H" -gravity center -quality 100 jpeg:"$FILE"
	fi
done
echo 'done'

# if you need to scale image you can use mogrify
# There is example below
# mogrify -adaptive-resize 800 -quality 70 -path new *.jpg