COMMAND.COM
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| Developer(s) | Seattle Computer Products, Microsoft, IBM, Novell |
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| Operating system | |
| Platform | x86 (16-bit) |
| Type | Command line interpreter |
COMMAND.COM is the default operating system shell for DOS operating systems and the default command line interpreter on Windows 95, Windows 98 and Windows ME. It has an additional role as the first program run after boot, hence being responsible for setting up the system by running the AUTOEXEC.BAT configuration file, and being the ancestor of all processes. COMMAND.COM's successor on OS/2 and Windows NT systems is CMD.EXE. COMMAND.COM is also available on IA-32 versions of those systems to provide compatibility when running DOS applications within the NTVDM.
COMMAND.COM is a DOS program. Programs executed by COMMAND.COM are DOS programs that use the MS-DOS API to communicate with the operating system (DOS).
As a shell, COMMAND.COM has two distinct modes of work. First is the interactive mode, in which the user types commands which are then executed immediately. The second is the batch mode, which executes a predefined sequence of commands stored as a text file with the extension .BAT.
Internal Commands are commands stored directly inside the COMMAND.COM binary. Thus, they can only be executed directly from the command interpreter.
All commands are run only after the Enter key is pressed at the end of the line. COMMAND.COM is not case-sensitive, meaning commands can be typed in any mixture of upper and lower case.
Control structures are mostly used inside batch files, although they can also be used interactively.
Batch files for COMMAND.COM can be said to have four kinds of variables:
Because DOS is a single-tasking operating system, piping is achieved by running commands sequentially, redirecting to and from a temporary file. COMMAND.COM makes no provision for redirecting the standard error channel.
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