如何将错误流重定向到变量 [英] How to redirect error stream to variable

问题描述

我有以下代码.我想获取错误流，在for循环中执行命令后将其放入变量中，与此同时，我将其发送到NUL来丢弃stdout.

I have the following piece of code. I want to take the error stream, put it in variable after executing the command in the for loop, and in the meantime I discard the stdout by sending it to NUL.

 for /f "delims=" %%a IN ('%test_command% 2^>^&1 1^>NUL') do (
           set err_msg="%%~a"
    )

我希望为其添加一项功能.除了将stdout发送到NUL之外，我还希望将其存储在文件中，该如何添加该功能?

I wish to add one feature to it. In addition to sending stdout to NUL I want to store it in a file, how do I to add that functionality ?

使用以下代码，我可以将输出存储到文件中:

Using the below code I can store the output to a file:

for /f "delims=" %%a IN ('%test_command% 2^>^&1 1^>temp.txt') do (
           set err_msg="%%~a"    
)

但是我想将输出存储到变量中，我该怎么做?

But I want to store the output to a variable, how can I do that?

推荐答案

仅存储第一行:

set /p var=<temp.txt

类似的东西:

do (
    set err_msg="%%~a" && set /p var=<temp.txt
)

要存储多行:

要从temp.txt中获取多行到一个变量中，请使用DelayedExpansion和第二个for循环:

To get multiple lines from temp.txt into a variable use DelayedExpansion and a second for loop:

setlocal EnableDelayedExpansion
...
for /f "Tokens=* Delims=" %%x in (temp.txt) do set var=!var!%%x

---

来源设置-显示，设置或删除CMD环境变量

要将文件的第一行放入变量中:

To place the first line of a file into a variable:

Set /P _MyVar=<MyFilename.txt

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