How to access local repository mirror?

I am trying to access a local apt mirror which is on a usb drive. The file tree on the drive is /apt-mirror /mirror /archive.ubuntu.com /dists /pool /skel /var The drive is /media/truecrypt1, so I added the following line to my sources list: deb file:///media/truecrypt1/apt-mirror trusty main restricted universe multiverse When I do sudo apt-get update I get lots of errors like: Err file: trusty/main Sources File not found Then it tries to reach http://us.archive.ubuntu.com which of course does not work because it is an offline machine, so I get a whole stream of errors while it fails to connect to that site. If I try to install a package, for example: sudo apt-get install astyle It tries to do it, but then fails because it cannot connect to us.archive.unbuntu.com. How can I make progress here?