#!/bin/bash

is_prime() {
    local number=$1
    if ((number <= 1)); then
        echo "false"
        return
    fi
    if ((number <= 3)); then
        echo "true"
        return
    fi
    if ((number % 2 == 0 || number % 3 == 0)); then
        echo "false"
        return
    fi
    local i=5
    while ((i * i <= number)); do
        if ((number % i == 0 || number % (i + 2) == 0)); then
            echo "false"
            return
        fi
        ((i += 6))
    done
    echo "true"
}

for i in {1..1000}
do
    if [ "$(is_prime "$i")" == "true" ]; then
        echo "$i is a prime number."
    else
        continue
    fi
done