如何在Bash / Ubuntu 12.04中正确编写此算术表达式？

Question

我无法以某种方式完成这项工作，

(( chunks = $size / $chunk_size + 1 ))
echo $chunks

修改

---

我也试过了，

chunks = $(( $size / $chunk_size + 1 ))

---

虽然这有效，

while [ $counter -le 10 ]; do
    echo $counter;
    (( counter++ ))
done

前者给我/ 157286400 + 1 ")syntax error: invalid arithmetic operator (error token is "，错误本身格式不正确。

Answer 1

您的$size变量未初始化或其中包含其他非数字字符。

$ chunk_size=157286400
$ unset size
$ (( chunks = $size / $chunk_size + 1 ))
-bash: ((: chunks =  / 157286400 + 1 : syntax error: operand expected (error token is "/ 157286400 + 1 ")
$ size=$'\r'  # carriage return
$ (( chunks = $size / $chunk_size + 1 ))
 / 157286400 + 1 ")syntax error: operand expected (error token is "

您可以通过修改AWK命令来删除回车符：

awk '/^Content-Length:/ { gsub("\015", "", $2); print $2 }'

Answer 2

确保初始化$ size和$ chunk_size ... 测试：

size=1
chunk_size=2
(( chunks = $size / $chunk_size + 1 ))
echo $chunks

Answer 3

试试这个：

let size=10
let chunk_size =2
declare -i chunks
let chunks =  $(($size / $($chunk_size + 1))))
echo $chunks