COMMAND.COM is the name for the default operating system shell (or command line interpreter) for DOS and 16/32bits versions of Windows (95/98/98 SE/Me). It also 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. It has been suggested that this article or section be merged into Shell_(computing). ... A command line interpreter is a computer program which reads lines of text that the user types and interprets them in the context of a given operating system or programming language. ... ‹ The template below has been proposed for deletion. ... Microsoft Windows is the name of several families of proprietary software operating systems by Microsoft. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows 98 (codenamed Memphis) is a graphical operating system released on June 25, 1998 by Microsoft and the successor to Windows 95. ... Windows 98 (codenamed Memphis) is a graphical operating system released on June 25, 1998 by Microsoft and the successor to Windows 95. ... Windows Me (IPA pronunciation: ), also known as Windows Millennium Edition is a hybrid 16-bit/32-bit graphical operating system released on September 14, 2000 by Microsoft. ... AUTOEXEC.BAT is the name of a system file found originally on the MS-DOS operating system. ...

Operating modes

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. Its function as the default command interpreter is analogous to that of the Unix shells, although COMMAND.COM's functionality is considerably more limited than that of its Unix counterparts. Wikibooks has more about this subject: Guide to Windows commands In MS-DOS, OS/2 and Windows, a batch file is a text file containing a series of commands intended to be executed by the command interpreter. ... Screenshot of a sample Bash session, taken on Gentoo Linux. ...

cmd.exe is COMMAND.COM's successor on Windows NT/2000/XP/2003 and OS/2. COMMAND.COM is also available on those systems to provide compatibility when running DOS applications. On NT systems, COMMAND.COM is run within the Virtual DOS Machine. cmd. ... Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Windows 2000 (also referred to as Win2K) is a preemptible, interruptible, graphical and business-oriented operating system that is designed to work with either uniprocessor or symmetric multi-processor 32-bit Intel x86 computers. ... Windows XP is a line of proprietary operating systems developed by Microsoft for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers. ... Windows Server 2003 is a server operating system produced by Microsoft. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Virtual DOS machine (VDM) is the name of Microsofts technologies allowing to run MS-DOS programs on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware. ...

Notable internal commands

All commands are run only after the Enter key is pressed at the end of the line. COMMAND.COM is case-insensitive, meaning commands can be typed in either case and are all equivalent (so dir, DIR and DiR will all work in the same way).

Filesystem commands

In accordance with COMMAND.COM's main function as an operating system shell, it includes a number of built-in commands for working with files.

In order to run a program, simply type the name of its executable and then press "Enter" (it is not necessary to use the extension, e.g. nc.exe can be summoned simply as nc). In order to change the current working drive (see Drive letter assignment), type its letter followed by a colon (e.g. D:). Other filesystem commands include: Drive letter assignment is the process of assigning drive letters to primary and logical partitions (drive volumes) in the root namespace; this usage is found in Microsoft operating systems. ...

DIR 

Lists the files in the current directory

CD, CHDIR 

Changes the current working directory or displays the current directory.

COPY 

Copies one file to another (if the destination file already exists, MS-DOS asks whether to replace it). (See also XCOPY, an external command that could also copy directory trees)

REN, RENAME 

Renames a file or directory

DEL, ERASE 

Deletes a file. When used on a directory, deletes all files in that directory, but does not recurse or delete the directory itself.

MD, MKDIR 

Creates a new directory

RD, RMDIR 

Removes an empty directory

VOL 

Shows information about a volume

LABEL 

Show or change the label of a volume

VERIFY 

Enable or disable verification of writing for files

TYPE 

Display the content of a file on the console

For computer operating systems that support a hierarchial file system, the working directory is the directory path that a user or program has designated to be the directory for files referenced by name only, or by a relative path (as contrasted with using both a files name and a... XCOPY is a command dating from DOS operating systems, but it is also available on Microsoft Windows. ...

Other commands

All commands from the interactive mode can be used in batch files; similarly, one can use batch-file commands directly on the COMMAND.COM command line, interactively. Therefore, it is impossible to separate the syntax to "interactive" or "batch" commands.

BREAK 

Controls the handling of program interruption with Ctrl+C.

CLS 

Clears the screen.

CHCP 

Displays or changes the current system code page.

CTTY 

Defines the device to use for input and output.

DATE 

Set the date of the system.

ECHO 

Toggles whether text is displayed (ECHO ON) or not (ECHO OFF). Also displays text on the screen (ECHO text).

LH, LOADHIGH 

Loads a program into upper memory.

LOCK 

Enables external programs to perform low-level disk access to a volume. (Windows 95/98/Me only)

PATH 

Displays or change the value of the PATH environment variable which controls the places where COMMAND.COM will search for executable files.

PAUSE 

Halts execution of the program and displays a message asking the user to press any key to continue.

PROMPT 

Displays or change the value of the PROMPT environment variable which controls the appearance of the prompt.

SET 

Sets the value of an environment variable ; Without arguments, shows all defined environment variables.

TIME 

Set the time of the system.

UNLOCK 

Disables low-level disk access. (Windows 95/98/Me only)

VER 

Displays the version of the operating system.

cls (for clear screen) is an MS-DOS command used to clear the screen of commands and any output generated by them. ... Code page is the traditional IBM term used for a specific character encoding table: a mapping in which a sequence of bits, usually a single octet representing integer values 0 through 255, is associated with a specific character. ... The Upper Memory Area (UMA) is a feature of the design of IBM PC-compatible x86 computers. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows 98 (codenamed Memphis) is a graphical operating system released on June 25, 1998 by Microsoft and the successor to Windows 95. ... Windows Me (IPA pronunciation: ), also known as Windows Millennium Edition is a hybrid 16-bit/32-bit graphical operating system released on September 14, 2000 by Microsoft. ... Environment variables are a set of dynamic values that can affect the way running processes will behave on a computer. ... This article or section does not cite its references or sources. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows 98 (codenamed Memphis) is a graphical operating system released on June 25, 1998 by Microsoft and the successor to Windows 95. ... Windows Me (IPA pronunciation: ), also known as Windows Millennium Edition is a hybrid 16-bit/32-bit graphical operating system released on September 14, 2000 by Microsoft. ... An operating system (OS) is a computer program that manages the hardware and software resources of a computer. ...

Undocumented commands

Some versions of MS-DOS COMMAND.COM recognized some internal commands which were not documented.

LFNFOR 

Enables or disables the return of long filenames by the FOR command. (Windows 95/98/Me only)

TRUENAME 

Display the "true name" of a file, by bypassing SUBST and ASSIGN filesystem mappings.

Long filename is the name given to the longer and therefore more descriptive titles on the FAT filesystem, which was previously restricted to eight characters and a three-character extension (referred to as 8. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows 98 (codenamed Memphis) is a graphical operating system released on June 25, 1998 by Microsoft and the successor to Windows 95. ... Windows Me (IPA pronunciation: ), also known as Windows Millennium Edition is a hybrid 16-bit/32-bit graphical operating system released on September 14, 2000 by Microsoft. ...

Control structures

Control structures are mostly used inside batch files, although they can also be used interactively.

:label 

Defines a target for GOTO.

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 (:likethis).

REM 

comment: any text following this command is ignored

IF 

Conditional statement, allows to branch the program execution

CALL 

Pauses execution of one batch file, runs another, and returns to the old one and continues.

EXIT 

Exits from Command.com and return to the program which launched it.

SHIFT 

Replaces each of the command-line variables with the consequent one (e.g. %0 with %1, %1 with %2 etc. )

In computer programming, a comment is a programming language construct that provides a mechanism for embedding information in the source code that is (generally) ignored by compilers and interpreters but may be of use to people reading the program source, or other programming tools that process the source such as...

Variables

Batch files for COMMAND.COM can be said to have four kinds of variables:

1. ERRORLEVEL - contains the return code of the last program to run that sets a value (an integer between 0 and 255). Most programs have a certain convention for their return codes (for instance, 0 for a successful execution). Some programs do not establish a new value, and thus the older value persists after they execute. The value of ERRORLEVEL is tested for range with the IF statement.
2. Environment variables - these have the form %VARIABLE% and are associated with values with the SET statement. Most versions of COMMAND.COM will only expand environment variables in batch mode.
3. Command-line parameters - these have the form %0, %1...%9, and initially contain the command name and the first nine command line parameters passed to the script (e.g., if the invoking command was "myscript.bat John Doe", then %0 is "myscript.bat", %1 is "John" and %2 is "Doe"). The parameters to the right of the ninth can be mapped into range by using the SHIFT statement.
4. "For" variables - used by loops, have the format %%a 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.

Environment variables are a set of dynamic values that can affect the way running processes will behave on a computer. ...

Redirection and piping

command < filename 

Redirect standard input from a file or device

command > filename 

Redirect standard output, overwriting target file if it exists.

command >> filename 

Redirect standard output, appending to target file if it exists.

command1 | command2 

Pipe standard output from command1 to standard input of command2

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. The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ... The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ... The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ... The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ... The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ... The standard streams for input, output, and error The standard streams are preconnected input or output channels between a computer program and its environment (typically a text terminal) when it begins execution. ...

Bugs/Limitations

The command line length, in interactive mode is limited to 128 characters. It always returns a true value upon executing a command. Del *.htm will delete also all .html files

Cultural references

"Loading COMMAND.COM" message can be seen on a HUD view of the Terminator and the internal viewport of Robocop when he reboots. HUD of a F/A-18C HUD of a MiG-29 HUD in a Pontiac Bonneville showing a speed of 47 mph A Head-Up Display, also known as a Heads-Up Display or simply HUD, is any type of display that presents data without blocking the users view. ... The T-800 was a cyborg, programmed to kill, in the fictional universe of the Terminator movies. ... RoboCop is a 1987 science fiction action movie and satire of business-driven capitalism, directed by Paul Verhoeven. ...

The COMMAND.COM is a position of authority in the show ReBoot. ReBoot was a Canadian animated series that was produced by Mainframe Entertainment, created by Gavin Blair, Ian Pearson, Phil Mitchell and John Grace, with character designed by Brendan McCarthy and Ian Gibson. ...

command.com was a website with an image of a command prompt with the "dir" command being run. It was meant to trick users into thinking the contents of their "C:" drive were deleted. However,the resulting command incorrectly displayed the . & .. directories, which were never shown in the root of a drive.

See also

• List of DOS commands
• Comparison of computer shells
• 4DOS
• CMD.EXE

A partial list of the most common commands for Microsofts MS-DOS operating system follows. ... A shell is a computer program which interacts with the userland and subsequently the kernel of an operating system. ... 4DOS is a command line interpreter by JP Software originally designed to replace the DOS default command. ... cmd. ...

External links

• Rob van der Woude's Scripting Pages
• Batfiles: The DOS batch file programming handbook & tutorial
• William and Linda Allen's Windows 95/98/ME ERRORLEVELs documentation (small ZIP file)
• command.com website (Internet Archive)