Iron Bars SHell is a restricted Unix shell. The user can not step out of, nor access, files outside the home directory. Two ASCII configuration files are used for more control. The system administrator can define which commands may be executed by the user. No other executables are allowed. The admin also has the opportunity to define what kind of files the user may create. If a file has a certain extension (such as .mp3, .c, etc.), ibsh automatically erases it.