Ubuntu :: Save The Output In A File (or Log) To Check If Error?

I have a bash script that i created for a colleague to configure the servers he installs. It does package installations, modifies some config files, creates directories.

The problem is sometimes he says that the script skips some steps. There are some steps that require user input and i think he chooses wrong option. (i have tested the script and it works fine).

My question is how can i save the output in a file (or log) so i can check if there are error? I know about the ">>" operators but will this "script.sh >> output.txt" still bring the dialogs for user input (like read input from shell and mysql password dialog from install package)? And how can i record everything he inputs?

I read about logger, but since there are a lot of commands do i have to log every command or can i just log the whole script.