#!/usr/bin/env bash read num echo nums=() for i in `seq 2 $num`; do nums+=($i) done unset nums[-1] while [ -n "$nums" ]; do prime=${nums[0]} echo $prime nums_=() for elem in "${nums[@]}"; do [ $(( $elem % $prime )) -eq 0 ] || nums_+=($elem) done nums=(${nums_[@]}) done