如何将stdout从一个进程重定向到另一个进程中的文件描述符3? [英] How do I redirect stdout from one process to be read as file descriptor 3 in another?

问题描述

我想将(stdout，stderr)从一个进程重定向到另一个进程的(stdin，文件描述符3).我该怎么办?

I want to redirect (stdout,stderr) from one process to (stdin,file descriptor 3) of another. How do I do that?

例如，如果我有myscript.sh:

#!/bin/sh
# myscript.sh
echo "stdout"
echo "stderr" >&2

和reader.sh:

#!/bin/sh
# reader.sh
read key
echo "stdin: $key"
read key <&3
echo "fd3: $key"

如何将myscript.sh的输出传递给reader.sh，使最终输出为:

How do I pipe the output of myscript.sh to reader.sh such that the final output is:

stdin: stdout
fd3: stderr

我最近得到的是:

./myscript.sh 2>&3 | ./reader.sh

但是挂起等待输入(来自fd 3)

But that hangs waiting for input (from fd 3)

推荐答案

我将使用命名管道来完成此操作:

I would do this with a named pipe:

mkfifo err 
./myscript.sh 2>err | ./reader.sh 3<err

执行2>& 3只会将stderr发送到父shell指向3的任何位置，如果您尚未在该shell中打开3，它将失败.这对阅读器外壳的3并没有任何好处.即使是继承的，也将是写fd，而不是读fd.

Doing 2>&3 in your attempt just sends stderr to wherever the parent shell has 3 pointed, and will fail if you haven't already opened 3 in that shell. It doesn't do any good for the reader shell's 3; even if inherited, it would be as a write fd, not a read one.

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