如何在bash中正确执行while循环？

Question

#!/bin/bash 

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

我不断收到错误

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

当在循环中运行./process.sh 5

Answer 1

的$手段，使$f “价值” 被评估为字符串文字1。所以......

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

应该

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

Answer 2

，它应该是

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