What is the way to separate command line output (processing from user interaction) on Unix?

Question

I'm writing a console application in which user interaction might be necessary (prompt for keyboard input, cli arguments etc.), but I want to keep it separate from the result of the processing (which goes to cout, in a way that it can be piped to some other application).

How can I achieve this, if I can't just send all interaction with the user to cerr (not everything is an error)?

Answer 1

/dev/tty是通常的方式，但是在大多数类似Unix的操作系统上，也可以从cerr / stderr读取，因为系统通常会在stdin和dup()将其打开到stdout和stderr打开一次tty。

Answer 2

当您的stdout通过管道传输到其他位置时，在终端上显示某些内容的唯一方法（除了诸如curses和dialog之类的东西）是stderr。

Answer 3

If you need user interaction, open /dev/tty, it will be the controlling terminal for the process. Standard error and standard input may be redirected as well.