error handling considers everything an error

Question

I made a short script that changes all files with one extension to a different extension. Both extensions are inputted by the user through command line arguments. I put in an if statement to handle errors but for some reason it considers everything an error and I am not sure why. I have pasted the script below. I am rather new to bash scripting so any help would be greatly appreciated!

if [[ "$#" == 0 ]] || [[ "$1" || "$2" != "."* ]]
 then

echo "Parameters are not valid"
exit
fi

for f in *"$1"; do
    name=${f%.*}
    mv $f "$name$2"
done

Answer 1

[[ "$1" || "$2" != "."* ]] [[ "$1" || "$2" != "."* ]] should be [[ "$1" != .* ]] || [[ "$2" != .* ]] [[ "$1" != .* ]] || [[ "$2" != .* ]]