在管道上将stdout与stderr区分开 [英] distinguish stdout from stderr on pipe

问题描述

popen()替代

我的问题与上面发布的一个问题有关.在第一个/被接受的响应中，我们正在做:

My question is related to one posted above. In the first/accepted response, we are doing:

// Child. Let's redirect its standard output to our pipe and replace process with tail
close(pipefd[0]);
dup2(pipefd[1], STDOUT_FILENO);
dup2(pipefd[1], STDERR_FILENO);

但是我想要的是将ERROR与常规OUTPUT区分开.我怎样才能做到这一点?当我在STDERR中得到任何东西时，我需要对此做出反应.

But what I want is to distinguish ERROR from regular OUTPUT. How can I do that? When I get anything in STDERR, I need to react to it.

这没有多大意义，但是，我可以执行以下操作吗?:

It does not make much sense but, can I do following?:

int pipefd[3]     /* instead of 2 */

dup2(pipefd[1], STDOUT_FILENO);
dup2(pipefd[2], STDERR_FILENO);

我正在使用select查看fd，并查看输出是否可用.但是直到现在，我只需要查看1 fd，现在我必须查看2.

I am using select to look at the fd and see if output is available. But till now, I just need to look at 1 fd, now I have to look at 2.

注意:管道只能有2个末端，对吗?一个要写，另一个要读.我如何容纳这个第三端:D ??

NOTE: A pipe can only have 2 ends, right? one to write to and other to read from. How can I accommodate this 3rd end :D ??

推荐答案

您需要创建两个独立的管道，并分别从中读取每个管道.因为您已经有一个select()，所以应该不难.

You need to create two independent pipes and read from each of them separately. Shouldn't be hard since you already have a select() in place.

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