There is not switch called "if". We generally use "if" statement in batch programming in DOS.

You don't, there is not usually a need to run any shutdown process in DOS, just switch it off.

DOS by default is not capable of multi-tasking. However, there are some shell and TSRs designed to allow you to switch between different DOS apps.

That depends on the programming interpreting the switches. Most MS-DOS programs used a / before each switch. Most Unix programs use a - before a series of switches.

Dos - Dos album - was created in 1986.