why there are a lot of free shell now can't use certain command?
Because there are two types of shells actually more but the most common is a Pre-validated shell. These shell account really suck. Most of the time you have to pay some type of fee to get a real shell. But it's to provide a benifit for the people who set up servers as a shell account it also blocks spammers, as well as hackers and alot of others. I used to use the Compaq test drive accounts, you forge some stupid survey and you have acces to 45 different boxes of you choice. They have freebsd, R.H.L., Suse, Openbsd, alot more I just don't remeber off the top of my head. They have a link at http:\\www.happyhacker.org you want to go to links, and then free shell accounts, they have a whole list of places to go to get a shell account.