bash 是否支持在读取循环中嵌套读取？
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Does bash support doing a read nested within a read loop?
提问by ddoxey
The bash read command is very convenient for:
bash 读取命令非常方便：
- read-p to prompt the user and capture input from the user
- while readloop to iterate through the lines of a file.
- read-p 提示用户并捕获用户的输入
- while read循环遍历文件的行。
However, I'm having issues attempting to do both simultaneously.
但是，我在尝试同时执行这两项操作时遇到了问题。
For example:
例如：
#!/bin/bash
while read item
do
echo Item: $item
read -p "choose wisely: " choice
echo You still have made a $choice.
done < /tmp/item.list
Rather than blocking and standing by for the user to enter a choice, bash is populating $choice with the next item in the item.list file.
bash 不是阻止和等待用户输入选择，而是用 item.list 文件中的下一个项目填充 $choice。
Does bash support doing a read nested within a read loop?
bash 是否支持在读取循环中嵌套读取？
回答by Steven Penny
The simplest fix is to have the outer readread from a different file
descriptor instead of standard input. In Bash, the -uoption make that a
little easier.
最简单的解决方法是read从不同的文件描述符而不是标准输入读取外部。在 Bash 中，该-u选项使这更容易一些。
while read -u 3 item
do
# other stuff
read -p "choose wisely: " choice
# other stuff
done 3< /tmp/item.list
