Short script to lock a binary behind a rofi/dmenu division quiz

math-locker.sh

#!/usr/bin/env bash
set -e

error() {
	echo "$1"
	echo
	echo "USAGE:"
	echo "$0 --lock name"
	echo "    locks the binary called name"
	echo "$0 --unlock name"
	echo "    unlocks the binary called name"
	echo "LICENSE: GPLv3"
	echo "AUTHOR: SEbbaDK"
	exit 1
}

if command -v rofi &> /dev/null ; then
	DMENU="rofi -dmenu"
elif command -v dmenu &> /dev/null ; then
	DMENU="dmenu"
else
	error "$0 requires either rofi or dmenu to be installed"
fi

lock() {
	path=$(which $1)
	newpath="$path-locked"
	mv "$path" "$newpath"
	cat > "$path" <<- EOF
		#!/usr/bin/env bash
		program="$newpath"

		correct=\$(shuf -n 1 -i 3-19)
		base=\$(shuf -n 1 -i 101-149)
		possibilities=\$(for i in {2..19}; do echo "\$i"; done)
		answer=\$(echo -e "\$possibilities" | $DMENU -p "\$base = \$(( \$correct * \$base )) / ??")
		[ \$correct == \$answer ] && \$program "\$@"
	EOF
	chmod +x "$path"
}

case "$1" in
	"--unlock"|"-u")
		[ -z "$2" ] && error "Give binary name to unlock"
		command -v "$2" &> /dev/null || error "Binary was not in path"
		path=$(which $2)
		[ ! -f "$path-locked" ] && error "This binary has not been locked"
		rm "$path"
		mv "$path-locked" "$path"
		;;
	"--lock"|"-l")
		[ -z "$2" ] && error "Give binary name to lock"
		command -v "$2" &> /dev/null || error "Binary was not in path"
		[ -f "$(which $2)-locked" ] && error "Binary already locked"
		lock $2
		;;
	*)
		error "Enter either --lock or --unlock to signify use"
esac