为什么" echo foo |读一个;回声$ a"不能按预期工作? [英] Why is "echo foo | read a ; echo $a" not working as expected?

问题描述

我可以在FreeBSD，GNU/Linux和Solaris下使用各种shell复制该问题.它让我头疼了一个多小时，所以我决定在这里发问.

I could replicate the problem with various shells under FreeBSD, GNU/Linux, and Solaris. It had me head-scratching for more than an hour, so I decided to post the question here.

推荐答案

由于使用了管道，因此read是在其自己的子shell中执行的.

Due to the piping the read is executed in its own subshell.

echo foo | while read a; do echo $a; done

将按照您的期望去做.

这篇关于为什么" echo foo |读一个;回声$ a"不能按预期工作?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！