In general, you need Unix-like shell and utilites, including awk. A Posix shell is required, bash works fine. You will also need GNU tar version 1.14, 1.15.1 or 1.15.91, and GNU Privacy Guard (gpg). The GnuPG passphrase agent, (gpg-agent) is supported though optional. The features described in the last two chapters dealing with Automake and CVS require GNU swbis version 0.499.