linux - 如何在 Bash/Ubuntu 12.04 中正确编写这个算术表达式？

Question

我无法以某种方式完成这项工作，

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

编辑

---

我也试过，

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

---

虽然这行得通，

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

前者给我 /157286400 + 1 ")syntax error: invalid arithmetic operator (error token is " and the error itself is not nicely formatted.

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 "

您可以像这样修改 AWK 命令来删除回车符:

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