Detect prime twins in bash

prime_neighbours.sh

#!/usr/bin/env bash

START=2
STOP=300

lastprime=2
primes=$(wget -O - -q http://www.math.utah.edu/~alfeld/math/p10000.html \
         | cut -c8- \
         | egrep -o '^ [0-9 ]+$' \
         | awk '{ list = list $0 } END { print list }')

for prime in $primes; do 
    if [ $prime -gt $STOP ]; then 
        break
    fi

    if [ $prime -lt $START ]; then 
        continue
    fi

    if [ $((prime - $lastprime)) -eq 2 ]; then 
        echo -e "$lastprime\t$prime"
    fi

    lastprime=$prime
done