Is it possible to install all packages from an APT repository?

That's a pretty ridiculous thing to do.

Edit: as suggested in other answers/comments, there are much easier ways to accomplish this through preexisting tools such as the package manager or aptitude. At any rate, the following describes where this information comes from. Their answers make more sense.

Ubuntu's repository locations can be found in /etc/apt/sources.list When you look in that file you'll probably see something like:

deb http://us.archive.ubuntu.com/ubuntu/ lucid universe restricted multiverse main

If you visit the url you can for example find the binary packages for lucid main for i386 at the following location:

http://us.archive.ubuntu.com/ubuntu/dists/lucid/main/binary-i386/

If you download archive file, there is file within that has a text file with the packages inside. By looking at it its easy to understand the format. For example, the first entry in the file:

Package: abrowser
Priority: optional
Section: web
Installed-Size: 132
Maintainer: Ubuntu Mozilla Team <[email protected]>
Architecture: all
Source: firefox
Version: 3.6.3+nobinonly-0ubuntu4
Replaces: abrowser-3.5, abrowser-3.6
Provides: abrowser-3.5, abrowser-3.6
Depends: firefox, abrowser-branding
Conflicts: abrowser-3.5 (<< 3.6~hg20100117r33523), abrowser-3.6 (<< 3.6~hg20100117r33523+nobinonly)
Filename: pool/main/f/firefox/abrowser_3.6.3+nobinonly-0ubuntu4_all.deb
Size: 79050
MD5sum: 109aa3010e292e951750d90d6b636122
SHA1: 23ba3fbea8c0a06619184d43f775e3d2b3ae1374
SHA256: c4cdf6cffc9f43194a9a6e52b9aa1495678f3f3c3847ef491fd5823aa5fba4a4
Description: metapackage for the unbranded abrowser
 ABrowser is an unbranded version of the popular Firefox webbrowser;
 it is written in the XUL language and designed to be lightweight and
 cross-platform.
 .
 This is a metapackage that will point to the latest abrowser package in
 your distribution.
 Don't remove this if you want to receive automatic major version upgrades
 for this package in future.
Xul-Appid: {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 3y

So you could then write a script that parses out each package name in the file and adds it to your 'sudo apt-get install' line...

...but that seems like a crazy thing to do. I imagine not all packages are going to agree with each other and do you really need EVERYTHING? It seems like an exercise in wasted time and resources for you and others.

links -http-proxy myproxyserver.com:8080 -dump http://repo.offensive-security.com/dist/bt4/binary/ | awk '{print $3}' | grep -i deb | cut -d . -f 1 > backtrack.txt

and then:

for i in $(cat backtrack.txt); do sudo aptitude -y install $i; done

Source:

http://micksmix.wordpress.com/2009/11/20/getting-the-backtrack-menu-structure-and-tools-in-ubuntu/

For installing backtrack utilities and menu structure in Ubuntu, download this and follow the readme instructions:

http://sourceforge.net/projects/backtrackubuntu/files/menu%20.zip/download