SQLPlus is a command line tool which allows you to store and retrieve data in Oracle, a relational database management system. Databases consist of tables that can be manipulated using SQL. SQL is a programming language used for managing databases. SQL queries are sent to the server using this SQLPlus tool. If you are using SQLPlus under Linux then you cannot rollback your command using the UP arrow or backspace button. This will display special characters. You need to use some existing commands such as L to review last command, R to redo last command, etc. You can install rlwrap package for Oracle in Linux when you are working with SQLPlus in a Linux environment to view previous commands.