1. Redirect stdout to one file and stderr to another file:

   command > out 2>error
   

2. Redirect stderr to stdout (&1), and then redirect stdout to a file:

   command >out 2>&1
   

3. Redirect both to a file:

   command &> out

https://askubuntu.com/questions/625224/how-to-redirect-stderr-to-a-file