The compsec= variable is automatically set during the boot process by command.com, and is
used to tell DOS where the transient portion of command.com is located.
Comspec=C:\command.com
The path= variable is used to tell command.com where to find the subdirectories that DOS is seeking when running a program.
Path=c:\dos; c:\windows
The Temp= statement is used to tell the operating system to store temporary files that are used by applications.
Set temp=c:\windows
The Prompt= is used to set the characteristics of the DOS prompt.
Prompt=$p$g
Prompt $p$g tells the operating system to have the prompt look as follows;
C:\>
The = sign in the above statements that are found in the autoexec.bat and config.sys represent an empty space. The commands will thus work without the = sign if there is a space between the variable and the statement.
The Echo command is used to repeat the text that is typed in, back to the screen and/or can be used to echo to a peripheral on the computer such as a COM port.
