Linux Bash：从文件中读取标准输入并将标准输出写入文件
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Bash: read stdin from file and write stdout to file
提问by alexandernst
I'm trying to run an app (let's say top) so it will read from a file for stdin and write to another file from stdout.
我正在尝试运行一个应用程序（假设top），因此它将从 stdin 的文件中读取并从 stdout 写入另一个文件。
Currently I have
目前我有
mkfifo stdin.pipe
(tail -f stdin.pipe) | top
which works as expected, as I can then echosomething to that file and top will receive it.
But I'm unable to redirect the output of top.
How can I achieve this?
它按预期工作，因为我可以echo对该文件进行一些操作，top 将收到它。但我无法重定向 top 的输出。我怎样才能做到这一点？
EDIT:
编辑：
Ok, let's scratch top. I'm testing with this:
好的，让我们从头开始。我正在测试这个：
cat test.sh
echo Say something
read something
echo you said $something
采纳答案by cdarke
Let's forget about top, that appears to be a red herring.
让我们忘记top，这似乎是一个红鲱鱼。
To map stdin or stdout to files, you can use redirection:
要将 stdin 或 stdout 映射到文件，您可以使用重定向：
some_program < input_file # Redirects stdin
another_program > output_file # Redirects stdout
or even:
甚至：
yet_another < input_file > output_file
回答by Joni
Is there a way I can map stdin and stdout to files and use them to control a cli app?
有没有办法可以将 stdin 和 stdout 映射到文件并使用它们来控制 cli 应用程序？
It sounds like you are looking for coprocesses, added to Bash in 4.0.
听起来您正在寻找在 4.0 中添加到 Bash 的coprocesses。
coproc cat # Start cat in background
echo Hello >&${COPROC[1]} # Say "Hello" to cat
read LINE <&${COPROC[0]} # Read response
echo $LINE # cat replied "Hello"!
Before 4.0 you had to use two named pipes to achieve this.
在 4.0 之前，您必须使用两个命名管道来实现这一点。
