Shell 脚本“for"循环语法 [英] Shell script "for" loop syntax

问题描述

我已经完成了以下工作:

I have gotten the following to work:

for i in {2..10}
do
    echo "output: $i"
done

它产生一堆output: 2、output: 3，依此类推.

It produces a bunch of lines of output: 2, output: 3, so on.

但是，尝试运行以下内容:

However, trying to run the following:

max=10
for i in {2..$max}
do
    echo "$i"
done

产生以下内容:

output: {2..10}

如何让编译器意识到它应该将 $max 视为数组的另一端，而不是字符串的一部分?

How can I get the compiler to realize it should treat $max as the other end of the array, and not part of a string?

推荐答案

大括号扩展，{x..y} 在其他扩展之前执行，因此您不能将其用于可变长度序列.

Brace expansion, {x..y} is performed before other expansions, so you cannot use that for variable length sequences.

相反，使用 seq 2 $max 方法作为 用户 mob 声明.

Instead, use the seq 2 $max method as user mob stated.

因此，对于您的示例，它将是:

So, for your example it would be:

max=10
for i in `seq 2 $max`
do
    echo "$i"
done

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