Renaming files in folder to a sequence of numbers
a=1
for i in *.jpg; do
new=$(printf "%04d.jpg" "$a") #04 pad to length of 4
mv -i -- "$i" "$new"
let a=a+1
done
a=1
for i in *.jpg; do
new=$(printf "%04d.jpg" "$a") #04 pad to length of 4
mv -i -- "$i" "$new"
let a=a+1
done