Get the backtrack gpg key and add to debian

The use of piping of adding the key.

If you are not familiar with piping this is what this long string of command means:
1. wget http://all.repository.backtrack-linux.org/backtrack.gpg
2. sudo apt-key add backtrack.gpg
wget http://all.repository.backtrack-linux.org/backtrack.gpg -O -
This means download backtrack.gpg and output to stdout (standard output stream)
sudo apt-key add -
This means add apt-key from the stdin (standard input stream)
wget http://all.repository.backtrack-linux.org/backtrack.gpg -O – | sudo apt-key add -
Add the repositories
Edit the file /etc/apt/sources.list with your favourite text editor.
#backtrack
deb http://all.repository.backtrack-linux.org revolution main microverse non-free testing
deb http://all.repository.backtrack-linux.org revolution main microverse non-free testing
deb http://all.repository.backtrack-linux.org revolution main microverse non-free testing
Update the apt database
sudo apt-get update
Without the gpg key apt-get will reject the database download. From here on you can download the pentest tools directly from backtrack-linux repositories.
Duplicates
Reading package lists… Done
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/main i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_main_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/microverse i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_microverse_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/non-free i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_non-free_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/testing i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_testing_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/main i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_main_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/microverse i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_microverse_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/non-free i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_non-free_binary-i386_Packages)
W: Duplicate sources.list entry http://all.repository.backtrack-linux.org/ revolution/testing i386 Packages (/var/lib/apt/lists/all.repository.backtrack-linux.org_dists_revolution_testing_binary-i386_Packages)
If you encounter duplicate sources.list run sudo apt-get update one more time.

source: http://cyruslab.wordpress.com/2012/02/11/debian-linux-add-backtrack-5-gpg-key-and-its-repositories/