<P> The format of options varies widely between operating systems . In most cases the syntax is by convention rather than an operating system requirement; the entire command line is simply a string passed to a program, which can process it in any way the programmer wants, so long as the interpreter can tell where the command name ends and its arguments and options begin . </P> <P> A few representative samples of command - line options, all relating to listing files in a directory, to illustrate some conventions: </P> <Table> <Tr> <Th> Operating system </Th> <Th> Command </Th> <Th> Valid alternative </Th> <Th> Notes </Th> </Tr> <Tr> <Td> OpenVMS </Td> <Td> directory / owner </Td> <Td> Dir / Owner </Td> <Td> instruct the directory command to also display the ownership of the files . Note the Directory command name is not case sensitive, and can be abbreviated to as few letters as required to remain unique . </Td> </Tr> <Tr> <Td> DOS </Td> <Td> dir / Q / O:S d * </Td> <Td> diR / qd * / o:s </Td> <Td> display ownership of files whose names begin with "D", sorted by size, smallest first . Note spaces around argument d * are required . </Td> </Tr> <Tr> <Td> Unix - like systems </Td> <Td> ls - lS D * </Td> <Td> ls - S - l D * </Td> <Td> display in long format files and directories beginning with "D" (but not "d"), sorted by size (largest first). Note spaces are required around all arguments and options, but some can be run together, e.g. - lS is the same as - l - S . </Td> </Tr> <Tr> <Td> Data General RDOS CLI </Td> <Td> list / e / s 04 - 26 - 80 / b </Td> <Td> List / S / E 4 - 26 - 80 / B </Td> <Td> list every attribute for files created before 26 April 1980 . Note the / B at the end of the date argument is a local switch, that modifies the meaning of that argument, while / S and / E are global switches, i.e. apply to the whole command . </Td> </Tr> </Table> <Tr> <Th> Operating system </Th> <Th> Command </Th> <Th> Valid alternative </Th> <Th> Notes </Th> </Tr>

List three example of software that used command line interface in real life application