Redirect the outputs and still see them when running a bash script

Question

My sysadmin created a bash script and the first command in it is to redirect the output in a log file:

exec > my_app.log

With this, I have the following:

• stdout redirected to my_app.log
• see stderr live in my terminal

When I manually execute the script, I want all of the following:

• stdout redirected to my_app.log
• stderr redirected to my_app.err
• see stdout live in my terminal
• see stderr live in my terminal

What do I need to change to the exec to have all that to happen?

Currently what I do is open 3 terminals.

• one to run the script with ./my_script.sh 2> my_app.err
• one to use tail -f my_app.log
• one to use tail -f my_app.err

This is too much I think.

Answer 1

Take a look at the following link wherein this question has been already answered. Read man page of tee for further details.

Answer 2

echo "hello" | tee file.txt

output from echo "hello" put to the file and stdout

if you need stderr and stdout, then echo "hello" 2>&1 | tee file.txt