Feta is a front end to various package management tools like dpkg, APT, and debconf. Feta provides a wrapper around these and other programs and tries to smooth out some of the inconsistencies between their normal interfaces. It also includes a teaching mode to help people learn to use the programs directly.
That description sums it up nicely on the surface. I think feta will be useful if it only saves me from forgetting whether I was supposed to type apt-get or apt-cache. Think of it as a one-stop tool for many of your apt/dpkg needs. There seems to be some odd error with the option parsing under Perl 5.8.3, but I haven't dug into it deeply. What I really like about feta (if you leave "teaching" mode on) is how it explains what commands it is actually running. feta also boasts bash programmable completion (but damned if I can get it to work, maybe I fubar'd my bash programmable completion again).
feta is brought to us today by Guido H. and Norbert K. (the latter having a small hand in hacking feta).
More information on this package can be found on the Debian web site.
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