Command-line Interfaces
A command-line interface is a way of interacting (sending instructions, receiving info) with programs on a computer.
See C->Processing Command-Line Input for how to write C code for dealing with command-line arguments passed to main().
Related is the page C#->Redirecting The Command-line To A Text Block.
Command Description (Help) Syntax
- Angled brackets for required parameters, e.g. 
cd <dir name>. - Square brackets for optional parameters, e.g. 
ls [-a]. - Ellipses for repeated items, e.g. 
cp <source1> [source2...]. - Vertical bars and curly braces when there is a choice of items (logical or), e.g. 
netstat {-t|-u}.