Why is STDERR redirected to STDOUT

I noticed tha开发者_Go百科t we have mainly 3 file streams. They are STDIN, STDOUT and STDERR.. My question is why is STDERR redirected to STDOUT?

stderr is not redirected to stdout. Both streams are only connected to the same device (the current screen or terminal) by default.

You can redirect them to different files:

$ command > stdout.log 2> stderr.log

In order to actually redirect stderr to stdout, you have to issue:

$ command 2>&1

It is not; it just happens that both stdout and stderr are typically mapped to the same output stream (usually the console). If you redirect stdout to a file for example you will find that stderr remains directed to the console.

The important point is that they are independently redirectable.

Like stdout, stderr is usually directed to the output device of the standard console (generally, the screen). That means, stderr is not redirected to stdout but they share a common file descriptor. It is possible to redirect stderr to some other destination from within a program using the freopen function.