Stderr

What is stderr, and please show an example of saving stderr to a file on a RHEL system. 

In Linux and Unix systems, stderr is a standard output stream that is used by programs to output error messages or diagnostic messages. By default, stderr is displayed on the terminal along with standard output (stdout), but it can be redirected to a file or another destination separately from stdout.

Here is an example of saving stderr to a file on a RHEL system:

Suppose you have a script called myscript.sh that produces both stdout and stderr output, and you want to redirect the stderr output to a file called errors.log. You can use the following command:

$ ./myscript.sh 2> errors.log

In this command, the 2> operator redirects stderr to the file errors.log, while stdout continues to be displayed on the terminal. The > operator redirects stdout to a file, so if you want to redirect both stdout and stderr to the same file, you can use:

$ ./myscript.sh &> errors.log

In this command, the &> operator redirects both stdout and stderr to the file errors.log.