In computing, a command is a high-level instruction received via an external interface that directs the behavior of a computer program. Commonly, commands are sent to a program via a command-line interface, a script, a network protocol, or as an event triggered in a graphical user interface.
Many commands support arguments to specify input and to modify default behavior. Terminology and syntax varies but there are notable common approaches. Typically, an option or a flag is a name (without whitespace) with a prefix such as dash or slash that modifies default behavior. An option might have a required value that follows it. Typically, flag refers to an option that does not have a following value. A parameter is an argument that specifies input to the command and its meaning is based on its position in the command line relative to other parameters; generally ignoring options. A parameter can specify anything, but often it specifies a file by name or path.