0 = Standard In
1 = Standard Out
2 = Standard Error
If you want all errors to be sent to Standard Out instead of
Standard In, append your command with 2>&1. This way, you can
pipe the output through something like tee, more, less, or
redirected to a file.
side note, if you want both stdout and stderr both redirected to a
file, say /tmp/output.txt, you can do that with a command
&>/tmp/output.txt