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COMMAND.COM is the default
command-line interpreter
A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...
for
MS-DOS
MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...
,
Windows 95
Windows 95 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of operating systems. The first operating system in the 9x family, it is the successor to Windows 3.1x, and was released to manufacturi ...
,
Windows 98
Windows 98 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. The second operating system in the 9x line, it is the successor to Windows 95, and was released to ...
and
Windows Me
Windows Millennium Edition, or Windows Me (marketed with the pronunciation of the pronoun "me"), is an operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It is the successor to Windo ...
. In the case of DOS, it is the default user interface as well. It has an additional role as the usual first program run after boot (init process), hence being responsible for setting up the system by running the
AUTOEXEC.BAT
AUTOEXEC.BAT is a system file that was originally on DOS-type operating systems. It is a plain-text batch file in the root directory of the boot device. The name of the file is an abbreviation of "automatic execution", which describes its funct ...
configuration file, and being the ancestor of all processes.
COMMAND.COM's successor on
OS/2
OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 r ...
and
Windows NT
Windows NT is a proprietary graphical operating system produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system.
The first version of Win ...
systems is
cmd.exe
Command Prompt, also known as cmd.exe or cmd, is the default command-line interpreter for the OS/2, eComStation, ArcaOS, Microsoft Windows (Windows NT family and Windows CE family), and ReactOS operating systems. On Windows CE .NET 4.2, Windo ...
, although COMMAND.COM is available in
virtual DOS machine
Virtual DOS machines (VDM) refer to a technology that allows running 16-bit/32-bit DOS and 16-bit Windows programs when there is already another operating system running and controlling the hardware.
Overview
Virtual DOS machines can operate eit ...
s on
IA-32
IA-32 (short for "Intel Architecture, 32-bit", commonly called i386) is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the 80386 microprocessor in 1985. IA-32 is the first incarnation o ...
versions of those operating systems as well.
The filename was also used by (DCP), an MS-DOS derivative by the former East German
VEB Robotron
VEB Kombinat Robotron (or simply Robotron) was the biggest East German electronics manufacturer. It was based in Dresden and employed 68,000 people (1989). It produced personal computers, SM EVM minicomputers, the ESER mainframe computers, se ...
.
The compatible command processor under
FreeDOS
FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems.
FreeDOS can ...
is sometimes also named
FreeCom
FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems.
FreeDOS ca ...
.
COMMAND.COM is a DOS program. Programs launched from COMMAND.COM are DOS programs that use the
DOS API
The DOS API is an API which originated with 86-DOS and is used in MS-DOS/ PC DOS and other DOS-compatible operating systems. Most calls to the DOS API are invoked using software interrupt 21h ( INT 21h). By calling INT 21h with a subfunctio ...
to communicate with the disk operating system.
Operating modes
As a shell, COMMAND.COM has two distinct modes of operation. The first is
interactive mode, in which the user types commands which are then executed immediately. The second is
batch mode
Computerized batch processing is a method of running software programs called jobs in batches automatically. While users are required to submit the jobs, no other interaction by the user is required to process the batch. Batches may automatically ...
, which executes a predefined sequence of commands stored as a text file with the
.BAT extension.
Internal commands
Internal commands are commands stored directly inside the COMMAND.COM binary. Thus, they are always available but can only be executed directly from the command interpreter.
All commands are executed after the 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.
;
BREAK
Break or Breaks or The Break may refer to:
Time off from duties
* Recess (break), time in which a group of people is temporarily dismissed from its duties
* Break (work), time off during a shift/recess
** Coffee break, a short mid-morning res ...
: Controls the handling of program interruption with or .
;
CHCP: Displays or changes the current system
code page.
;
CHDIR, CD: Changes the current
working directory
In computing, the working directory of a process is a directory of a hierarchical file system, if any, dynamically associated with each process. It is sometimes called the current working directory (CWD), e.g. the BSD getcwd function, or just c ...
or displays the current directory.
;
CLS: Clears the screen.
;
COPY
Copy may refer to:
*Copying or the product of copying (including the plural "copies"); the duplication of information or an artifact
**Cut, copy and paste, a method of reproducing text or other data in computing
**File copying
**Photocopying, a pr ...
: Copies one file to another (if the destination file already exists, MS-DOS asks whether to replace it). (See also
XCOPY
In computing, XCOPY is a command used on IBM PC DOS, MS-DOS, IBM OS/2, Microsoft Windows, FreeDOS, ReactOS, and related operating systems for copying multiple files or entire directory trees from one directory to another and for copying files a ...
, an external command that could also copy directory trees).
;
CTTY: Defines the device to use for input and output.
;
DATE
Date or dates may refer to:
*Date (fruit), the fruit of the date palm (''Phoenix dactylifera'')
Social activity
*Dating, a form of courtship involving social activity, with the aim of assessing a potential partner
** Group dating
*Play date, a ...
: Display and set the date of the system.
;
DEL, ERASE: Deletes a file. When used on a directory, deletes all files inside the directory only. In comparison, the external command
DELTREE
In computing, DELTREE (short for ''delete tree'') is a command line command in some Microsoft operating systems, SpartaDOS X and FreeDOS that recursively deletes an entire subdirectory of files.
Overview
When IBM and Microsoft introduced PC DOS 1 ...
deletes all subdirectories and files inside a directory as well as the directory itself.
;
DIR: Lists the files in the specified directory.
;
ECHO
In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the lis ...
: Toggles whether text is displayed () or not (). Also displays text on the screen ().
;
EXIT
Exit(s) may refer to:
Architecture and engineering
* Door
* Portal (architecture), an opening in the walls of a structure
* Emergency exit
* Overwing exit, a type of emergency exit on an airplane
* Exit ramp, a feature of a road interchange
...
: Exits from COMMAND.COM and returns to the program which launched it.
;
LFNFOR: Enables or disables the return of
long filenames by the FOR command. (
Windows 9x
Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, both of which were updated in su ...
).
;
LOADHIGH, LH: Loads a program into
upper memory
In DOS memory management, the upper memory area (UMA) refers to memory between the addresses of 640 KB and 1024 KB ( 0xA0000–0xFFFFF) in an IBM PC or compatible. IBM reserved the uppermost 384 KB of the 8088 CPU's 1024 KB ...
( in
DR DOS
DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in 1988, it was the first DOS attempting to be compatible with IBM PC DOS and MS-D ...
).
;
LOCK
Lock(s) may refer to:
Common meanings
*Lock and key, a mechanical device used to secure items of importance
*Lock (water navigation), a device for boats to transit between different levels of water, as in a canal
Arts and entertainment
* ''Lock ...
: Enables external programs to perform low-level disk access to a volume. (
MS-DOS 7.1 and
Windows 9x
Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, both of which were updated in su ...
only)
;
MKDIR, MD: Creates a new directory.
;
PATH
A path is a route for physical travel – see Trail.
Path or PATH may also refer to:
Physical paths of different types
* Bicycle path
* Bridle path, used by people on horseback
* Course (navigation), the intended path of a vehicle
* Desire p ...
: Displays or changes the value of the PATH
environment variable
An environment variable is a dynamic-named value that can affect the way running processes will behave on a computer. They are part of the environment in which a process runs. For example, a running process can query the value of the TEMP envi ...
which controls the places where COMMAND.COM will search for executable files.
;
PROMPT
Prompt may refer to:
Computing
* Command prompt, characters indicating the computer is ready to accept input
* Command Prompt, also known as cmd.exe or cmd, the command-line interpreter in some operating systems
* Prompt (natural language), instr ...
: Displays or change the value of the PROMPT environment variable which controls the appearance of the prompt.
;
RENAME, REN: Renames a file or directory.
;
RMDIR, RD: Removes an empty directory.
;
SET
Set, The Set, SET or SETS may refer to:
Science, technology, and mathematics Mathematics
*Set (mathematics), a collection of elements
*Category of sets, the category whose objects and morphisms are sets and total functions, respectively
Electro ...
: Sets the value of an
environment variable
An environment variable is a dynamic-named value that can affect the way running processes will behave on a computer. They are part of the environment in which a process runs. For example, a running process can query the value of the TEMP envi ...
; without arguments, shows all defined environment variables.
;
TIME
Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, ...
: Display and set the time of the system.
;
TRUENAME
A true name is a name of a thing or being that expresses, or is somehow identical to, its true nature. The notion that language, or some specific sacred language, refers to things by their true names has been central to philosophical study as we ...
: Display the fully expanded physical name of a file, resolving
ASSIGN,
JOIN Join may refer to:
* Join (law), to include additional counts or additional defendants on an indictment
*In mathematics:
** Join (mathematics), a least upper bound of sets orders in lattice theory
** Join (topology), an operation combining two top ...
and
SUBST
In computing, SUBST is a command on the DOS, IBM OS/2, Microsoft Windows and ReactOS operating systems used for substituting paths on physical and logical drives as virtual drives.
Overview
In MS-DOS, the SUBST command was added with the rel ...
logical filesystem mappings.
;
TYPE: Display the content of a file on the console.
;
UNLOCK: Disables low-level disk access. (MS-DOS 7.1 and
Windows 9x
Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, both of which were updated in su ...
only)
;
VER Ver or VER may refer to:
* Voluntary Export Restraints, in international trade
* VER, the IATA airport code for General Heriberto Jara International Airport
* Volk's Electric Railway, Brighton, England
* VerPublishing, of the German group VDM P ...
: Displays the version of the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
.
;
VERIFY
CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residing ...
: Enable or disable verification of writing for files.
;
VOL:Shows information about a volume.
Batch file commands
Control structures are mostly used inside batch files, although they can also be used interactively.
;
:''label'': Defines a target for GOTO.
;
CALL
Call or Calls may refer to:
Arts, entertainment, and media Games
* Call, a type of betting in poker
* Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage
Music and dance
* Call (band), from Lahore, Paki ...
: Executes another batch file and returns to the old one and continues.
;
FOR: Iteration: repeats a command for each out of a specified set of files.
;
GOTO: Moves execution to a specified label. Labels are specified at the beginning of a line, with a colon ().
;
IF: Conditional statement, allows branching of the program execution.
;
PAUSE: Halts execution of the program and displays a message asking the user to press
any key to continue.
;
REM:
comment
Comment may refer to:
* Comment (linguistics) or rheme, that which is said about the topic (theme) of a sentence
* Bernard Comment (born 1960), Swiss writer and publisher
Computing
* Comment (computer programming), explanatory text or informa ...
: any text following this command is ignored.
;
SHIFT: Replaces each of the
replacement parameters with the subsequent one (e.g. with , with , etc.).
IF command
On exit, all external commands submit a
return code
In computer programming, a return code or an error code is a numeric or alphanumeric code that is used to determine the nature of an error and why it occurred. They are also commonly found in consumer electronics and devices when they attempt to ...
(a value between 0 and 255) to the calling program. Most programs have a certain convention for their return codes (for instance, 0 for a successful execution).
If a program was invoked by COMMAND.COM, the internal IF command with its ERRORLEVEL conditional can be used to test on error conditions of the last invoked external program.
Under COMMAND.COM, internal commands do not establish a new value.
Variables
Batch files for COMMAND.COM can have four kinds of variables:
*
Environment variable
An environment variable is a dynamic-named value that can affect the way running processes will behave on a computer. They are part of the environment in which a process runs. For example, a running process can query the value of the TEMP envi ...
s: These have the form and are associated with values with the SET statement. Before DOS 3 COMMAND.COM will only expand environment variables in batch mode; that is, not interactively at the command prompt.
*
Replacement parameters: These have the form , ..., and initially contain the command name and the first nine
command line parameters passed to the script (e.g., if the invoking command was , then is "myscript.bat", is "John" and is "Doe"). The parameters to the right of the ninth can be mapped into range by using the SHIFT statement.
* Loop variables: Used in loops, they have the format when run in batch files. These variables are defined solely within a specific FOR statement, and iterate over a certain set of values defined in that FOR statement.
* Under
Novell DOS 7
DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in 1988, it was the first DOS attempting to be compatible with IBM PC DOS and MS-D ...
,
OpenDOS 7.01
DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in 1988, it was the first DOS attempting to be compatible with IBM PC DOS and MS-D ...
,
DR-DOS 7.02
DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in 1988, it was the first DOS attempting to be compatible with IBM PC DOS and MS-D ...
and higher, COMMAND.COM also supports a number of
system information variables,
a feature earlier found in
4DOS 3.00 and higher
as well as in
Multiuser DOS
Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers.
An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by ...
,
although most of the supported variable names differ.
Redirection, piping, and chaining
Because DOS is a single-tasking operating system,
piping
Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid.
Industrial process piping (and accompa ...
is achieved by running commands sequentially, redirecting to and from a
temporary file
A temporary file is a file created to store information temporarily, either for a program's intermediate use or for transfer to a permanent file when complete. It may be created by computer programs for a variety of purposes, such as when a program ...
. COMMAND.COM makes no provision for redirecting the
standard error
The standard error (SE) of a statistic (usually an estimate of a parameter) is the standard deviation of its sampling distribution or an estimate of that standard deviation. If the statistic is the sample mean, it is called the standard error o ...
channel.
;
''command'' < ''filename''
: Redirect
standard input
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...
from a file or device
;
''command'' > ''filename''
: Redirect
standard output
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...
, overwriting target file if it exists.
;
''command'' >> ''filename''
: Redirect
standard output
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...
, appending to target file if it exists.
;
''command1'' , ''command2''
: Pipe
standard output
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...
from ''command1'' to
standard input
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...
of ''command2''
;
''command1'' ¶ ''command2''
:
: Commands separated by ASCII-20 (¶, invoked by ) are executed in sequence (chaining of commands).
In other words, first ''command1'' is executed until termination, then ''command2''.
This is an undocumented feature in COMMAND.COM of
MS-DOS
MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...
/
PC DOS 5.0 and higher.
It is also supported by COMMAND.COM of the Windows NT family as well as by DR-DOS 7.07. All versions of DR-DOS COMMAND.COM already supported a similar internal function utilizing an exclamation mark (!) instead (a feature originally derived from
Concurrent DOS and
Multiuser DOS
Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers.
An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by ...
) - however, in the single-user line this feature was only available internally (in built-in startup scripts like "!DATE!TIME") and indirectly through
DOSKEY
DOSKEY is a command for DOS, IBM OS/2, Microsoft Windows, and ReactOS that adds command history, macro functionality, and improved editing features to the command-line interpreters COMMAND.COM and cmd.exe.
History
The command was included as ...
's $T parameter to avoid problems with ! as a valid filename character.
4DOS
4DOS is a command-line interpreter by JP Software, designed to replace the default command interpreter COMMAND.COM in Microsoft DOS and Windows. It was written by Rex C. Conn and Tom Rawson and first released in 1989. Compared to the default, ...
supports a configurable command line separator (
4DOS.INI CommandSep= or SETDOS /C), which defaults to ^.
COMMAND.COM in newer versions of Windows NT also supports an separator for compatibility with the cmd syntax in OS/2 and the Windows NT family.
(cmd, however, does not support the ¶ separator.)
Limitations
The command line length in interactive mode is limited to 126 characters.
In popular culture
The message "Loading COMMAND.COM" can be seen on a
HUD
Hud or HUD may refer to:
Entertainment
* ''Hud'' (1963 film), a 1963 film starring Paul Newman
* ''Hud'' (1986 film), a 1986 Norwegian film
* ''HUD'' (TV program), or ''Heads Up Daily'', a Canadian e-sports television program
Places
* Hud, Fa ...
view of the
Terminator
Terminator may refer to:
Science and technology
Genetics
* Terminator (genetics), the end of a gene for transcription
* Terminator technology, proposed methods for restricting the use of genetically modified plants by causing second generation s ...
and the internal viewport of
RoboCop when he reboots.
In the CGI children's TV series ''
ReBoot
In computing, rebooting is the process by which a running computer system is restarted, either intentionally or unintentionally. Reboots can be either a cold reboot (alternatively known as a hard reboot) in which the power to the system is physi ...
'', which takes place inside computers, the leader of a system (the equivalent of a city) is called the COMMAND.COM.
See also
* (starts the command processor as the first process)
*
SHELL (CONFIG.SYS directive)
CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residing ...
(to override default command processor)
*
COMSPEC (environment variable)(set by COMMAND.COM to reload transient portion of itself)
*
CMDLINE (environment variable)(set by COMMAND.COM to pass long command lines to external programs)
* (third-party replacement command processors)
*
DOSSHELL
DOS Shell is a file manager that debuted in MS-DOS and PC DOS version 4.0, released in June 1988. It was discontinued in MS-DOS version 6.22, but remained part of the Supplemental Disk. The Supplemental Disk could be ordered or could be do ...
/
ViewMAX
ViewMAX is a CUA-compliant file manager supplied with DR DOS versions 5.0 and 6.0. It is based on a cut-down runtime version of Digital Research's GEM/3 graphical user interface modified to run only a single statically built applicatio ...
(alternative DOS shells)
*
List of DOS commands
This article presents a list of commands used by DOS operating systems, especially as used on x86-based IBM PC compatibles (PCs). Other DOS operating systems are not part of the scope of this list.
In DOS, many standard system commands were pro ...
*
Comparison of command shells
A command shell is a command-line interface to interact with and manipulate a computer's operating system.
General characteristics
Interactive features
Background execution
Background execution allows a shell to run a command without us ...
* (have similar command processors not named COMMAND.COM)
*
PC-MOS/386
PC-MOS/386 is a multi-user, multitasking computer operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating ...
(has a similar command processor also named COMMAND.COM)
*
Transient Program Area
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
(TPA)
(area available for use either by the running application or the transient portion of COMMAND.COM)
*
SpartaDOS X
SpartaDOS X (or SpartaDOS 4.0) is a disk operating system for the Atari 8-bit family of computers that closely resembles MS-DOS. It was developed and sold by ICD, Inc. in 1987-1993, and many years later picked up by the third-party community S ...
(a similar implementation for Atari computers)
References
Further reading
*
*
*
*
External links
* – Source code to COMMAND.COM version 2.11 released by Microsoft as part of MS-DOS 2.0
* – Source code to COMMAND.COM version 1.17 released by Microsoft as part of MS-DOS 1.25
FreeCom– COMMAND.COM implementation of FreeDOS
{{DOS system files
Command shells
DOS command shells
Windows command shells
Scripting languages
DOS files
Windows files
External DOS commands
MSX-DOS