如何在bash中正确执行此循环？

Question

#!/bin/bash

f=1
c=$1
while [[ $c != 0 ]]
do
        $f=$(($c*$f))
        $c=$(($c-1))
done
echo $c

我一直收到错误

./process.sh: line 8: 1=0: command not found
./process.sh: line 7: 5=5: command not found

运行./process.sh 5

时

Answer 1

$表示“值”，因此$f会对字符串文字1进行评估。所以......

    $f=$(($c*$f))
    $c=$(($c-1))

应该是

    f=$(($c*$f))
    c=$(($c-1))

Answer 2

在循环中，它应该是

f=$(($c*$f))
c=$(($c-1))