python - Shell 脚本主要文本

Question

我正在尝试从 Python ( What is the best algorithm for checking if a number is prime? ) “转换”为 Shell 脚本。这是我的想法(可能是非常愚蠢的代码):

#!/bin/bash
prime (){
i=5
w=2
while [ `echo "$i*$i" | bc -l ` -le $n ]
    do
      if [ n % i -eq 0 ]
        then echo "$n is not prime"
      else
        i = i + w
        w = 6 - w
        echo "$n is prime"
    fi
done
}
echo "Test for knowing if a number is prime or not."
sleep 2
echo "Enter the number"
read n
if [ $n -eq 1 ]
   then echo "Number 1 is not prime"
elif [ $n -eq 2 ]
   then echo "Number two is prime"
elif [ $n -eq 3 ]
   then echo "Number three is prime"
else
   prime
fi

问题是当我输入任何其他数字(4、5、6...)时，无论 $n 是否为素数，程序都不会返回。如果有人能帮助我，我将非常感激。

Answer 1

如果您可以从 GNU 核心实用程序访问 factor:

f=$(factor 11 | wc -w); [[ $f -eq 2 ]] && echo prime || echo not prime

输出:

prime

---

f=$(factor 6 | wc -w); [[ $f -eq 2 ]] && echo prime || echo not prime

输出:

not prime