P7zip

p7zip is a command-line port of 7-Zip for POSIX compliant systems such as Unix, OS X, BeOS and Amiga. Created by Igor Pavlov, the 7-Zip compression type uses one of the highest compression ratios currently available. Since version 4.10 it supports little and big endian machines.

Emerge
p7zip can be installed by running:

Usage
To extract all files from an archive to the current directory without using directory names, use the following command:

Where  is to be replaced with the archive's name.

To extract with full paths, use the following command:

To extract into a new directory, use the following command:

Where  is the name of the new folder.