Hello,

I have installed auto-apt using instructions:

https://help.ubuntu.com/community/AutoApt

but the problem is I cannot execute it

bash: apt-file: command not found

probably it could be in some directory, but there is not in enviroment variable. So how can I find where it is inslled?

The command to search for packages is apt-cache search, not apt-file. It does not need root permission to run, unlike apt-get. According to the instructions of the page you gave, auto-apt search would work for this utility.

auto-apt get installed into /usr/lib/auto-apt You should see it there.

I can install this on Mint 13 with no issues.

Do you not have this file?

I was reading this:
https://help.ubuntu.com/community/CompilingEasyHowTo

and did not do this:

You probably want to read about the possibilities and limitations of auto-apt first, which will attempt to take care of dependency issues automatically. The following instructions are for fulfilling dependencies manually:
To prepare, install the package apt-file, and then run sudo apt-file update.

so thats why it was not found, needed to install first apt-file.

So this is solved for now at least.