1 If your wooden pallets contain low-grade engineered wood or cardboard, they may also contain formaldehyde and harbor all kinds of critters you don't want to know about.
Command shell overview. The command shell is a separate software program that provides direct communication between the user and the operating system. The non-graphical command shell user interface provides the environment in which you run character-based applications and utilities.
The Unix shell is both an interactive command language as well as a scripting programming language, and is used by the operating system as the facility to control (shell script) the execution of the system. Shells created for other operating systems often provide similar functionality.