The only command line interface tweak available is Mobile Terminal (free in Cydia).
The older version that was available in Cydia, v364.1-10, was old and did not work on iOS 5. The newer version, v520-1, was available to install once you found it on the web with a search and installed it manually with SSH or iFile.
The good news is that, just a couple of days ago, Cydia was [finally!] updated and you can now easily get an updated version of Mobile Terminal (v520-2). Just go to Cydia and search for it; then, it's a normal download from Cydia. This works fine on my iPad3 running iOS 5.1.1.
Again, this is the only tweak I know of for this purpose.
Marilyn