如何做一个while循环使用重定向到它串 [英] How to do a while loop with a string redirected into it

问题描述

我试着去环，虽然里面HTTP链接和换行符的字符串，我要循环线路在同一时间。

Im trying to loop though a string with HTTP links inside and newlines, I want to loop over a line at a time.

目前，我有

echo -e "$HTTP_LINKS" | while read HTTP_S_LINK ; do
    TEST_STRING="test"
done

不过这样一来，我没有访问TEST_STRING出的圈，这就是我想要的。
我使用whil​​e循环，使其循环尽管在$ HTTP_LINKS而不仅仅是字符串中的字，每个换行。 （我不想用一个for循环与IFS设置为\\ n）

But this way I don't have access to the TEST_STRING out side the loop, which is what I want. I'm using the while loop so that it will loop though each newline in $HTTP_LINKS and not just the words in the string. (I don't want to use a for loop with IFS set to \n)

我想也许我可以做这样的事情。

I thought maybe I could just do something like this

#!/bin/bash
while read HTTP_S_LINKS
do   
    TEST_STRING="test2"
done < $HTTP_LINKS

不过，当然这不工作为$ HTTP_LINKS包含一个字符串，而不是一个链接到一个文件中。

But of course this doesn't work as $HTTP_LINKS contains a string and not a link to a file.

推荐答案

您曾与你的第二snipit正确的想法，但需要通过使用'这里字符串'的＆LT;＆LT;＆LT; 语法。你不能访问 $ TEST_STRING 你的第一个snipit之外，因为管道创建一个子shell;使用下面的字符串没有。此外，请确保你引用$ HTTP_LINKS，否则你将失去换行。

You had the right idea with your 2nd snipit but you need to use 'Here Strings' via the <<< syntax. You cant access $TEST_STRING outside of your first snipit because the pipe creates a sub-shell; using the here-string does not. Also, make sure you quote "$HTTP_LINKS" otherwise you'll lose the newlines.

#!/bin/bash

HTTP_LINKS=$(echo -e "http://www.aaa.com\nhttp://www.bbb.com")

unset TEST_STRING; 

while read url; 
do 
    ((TEST_STRING++))
done <<<"$HTTP_LINKS"

echo $TEST_STRING

输出

2

这篇关于如何做一个while循环使用重定向到它串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！