从.sh文件执行时，bash foreach循环的工作方式有所不同 [英] Bash foreach loop works differently when executed from .sh file

问题描述

以下单人"可以满足我的需求:

The following 'oneliner' does what I need:

$ for i in {1..5}; do echo $i; done
1
2
3
4
5

但是，当我将完全相同的代码放入for-each.sh文件中并执行它时，我得到了不同的结果.为什么?

However, when I place exactly the same code into for-each.sh file and execute it, I get different result. Why?

for-each.sh文件:

for-each.sh file:

#!/bin/bash
for i in {1..10}; do echo $i; done

执行后的结果:

$ ./for-each.sh
{1..10}

编辑

Uf.抱歉.现在我注意到我是通过sh ./for-each.sh命令而不是通过./for-each.sh命令执行for-each.sh的.我不知道bash，sh，破折号和...之间的区别……阅读 stackoverflow.com/a/5725402/915756 a>我意识到我在Debian机器上默认使用短划线来执行文件，该文件指向/bin/sh.

Uf. I'm sorry. Now I noticed that I executed the for-each.sh by sh ./for-each.sh command and not by ./for-each.sh. I didn't know the difference between bash, sh, dash, ... After reading stackoverflow.com/a/5725402/915756 I realized that I executed the file by dash which points to /bin/sh by default on my Debian machine.

推荐答案

如果您确信它确实是bash执行脚本，则可以明确打开括号扩展(扩展{...}表达式)，如下所示:

If you're confident that it is indeed bash executing your script, you can explicitly turn on brace expansion (expansion of {...} expressions) as follows:

set -B   # same as: set -o braceexpand

在执行完爆炸后，将其作为脚本的第一个命令. (相反，set +B(set +o braceexpand)会关闭括号扩展名.)

Make this your script's first command after your shebang. (Conversely, set +B (set +o braceexpand) would turn brace extension OFF.)

可以想象，您的系统被配置为默认情况下关闭括号扩展.

Conceivably, your system is configured to have brace extension turned off by default.

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