#!/bin/bash
# basic_sieve
# The Sieve of Eratosthenes (basic version)

M=$1
N=$(echo "scale=0;sqrt($M)+1" | bc)
P=( $(seq 2 $M) )

j=0
while test $j -le $N; do
  if test -n "${P[$j]}"; then
    k=$j
    until test $k -gt $M; do
      let k+=${P[$j]}
      unset P[$k]
    done
  fi  
  let j=$j+1
done  
echo ${P[*]}