Custom build system error

[jimi]

Hello all,
I created a new build system that build my files and launch a bash script
"cmd": ["python", "-u", "$file"],
"file_regex": "^[ ]*File \"(...*?)\", line ([0-9]*)",
"selector": "source.python",
"cmd": ["/copytodebian.sh"]

It works correctly, but if there is an error on my python source I can't see the error on the console.
I always see the bash output:
Copy file...
Copy Completed

So, is there a way to see the python build output? and ins there a way to stop the bash if there is an error?

Thank you
J.
Sorry for my English I still learn.