COMMAND.COM: Difference between revisions

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
VisualWikitext
imported>CodingKoopa
m Undid revision 1279556552 by 152.59.36.157 (talk): Vandalism
 
imported>Cewbot
m Normalize {{Multiple issues}}: Remove {{Multiple issues}} for only 1 maintenance template: More citations needed
 
(2 intermediate revisions by 2 users not shown)
Line 2: Line 2:
{{Redirect|COMMAND|other uses|Command (disambiguation){{!}}Command}}
{{Redirect|COMMAND|other uses|Command (disambiguation){{!}}Command}}
{{distinguish|cmd.exe}}
{{distinguish|cmd.exe}}
{{Use list-defined references|date=December 2021}}
{{More citations needed|date=September 2025}}
{{Use dmy dates|date=April 2019|cs1-dates=y}}
{{Use dmy dates|date=April 2019|cs1-dates=y}}
{{Use list-defined references|date=December 2021}}
{{Infobox software
{{Infobox software
| name = COMMAND.COM
| name = {{mono|COMMAND.COM}}
| screenshot = Command.com Win10.png
| screenshot = Command.com Win10.png
| caption = COMMAND.COM in [[Windows 10]]
| caption = {{mono|COMMAND.COM}} in [[Windows 10]]
| other_names = MS-DOS Prompt,<br />Windows Command Interpreter
| other_names = MS-DOS Prompt,<br />Windows Command Interpreter
| developer = [[Seattle Computer Products]], [[IBM]], [[Microsoft]], [[The Software Link]], [[Datalight]], [[Novell]], [[Caldera UK|Caldera]]
| developer = [[Seattle Computer Products]], [[IBM]], [[Microsoft]], [[The Software Link]], [[Datalight]], [[Novell]], [[Caldera UK|Caldera]]
| released = {{Start date and age|1980}}
| released = {{Start date and age|1980}}
| replaced_by = [[cmd.exe]]
| replaced_by = {{mono|[[cmd.exe]]}}
| programming language = [[x86]] [[assembly language]]<ref name="Microsoft_COMMAND"/>
| programming language = [[x86]] [[assembly language]]<ref name="Microsoft_COMMAND"/>
| operating_system = {{ubl|[[86-DOS]]|[[MS-DOS]]|[[PC&nbsp;DOS]]|[[DR-DOS]]|[[SISNE plus]]|[[PTS-DOS]]|[[ROM-DOS]]|[[OS/2]]|[[Windows 9x]]|[[Windows NT]] ([[NTVDM]])|[[FreeDOS]]|[[MSX-DOS]]}}
| operating_system = {{ubl|[[86-DOS]]|[[MS-DOS]]|[[PC&nbsp;DOS]]|[[DR-DOS]]|[[SISNE plus]]|[[PTS-DOS]]|[[ROM-DOS]]|[[OS/2]]|[[Windows 9x]]|[[Windows NT]] ([[NTVDM]])|[[FreeDOS]]|[[MSX-DOS]]}}
Line 17: Line 18:
| genre = [[Command-line interpreter]]
| genre = [[Command-line interpreter]]
}}
}}
[[File:Microsoft Windows 95 Version 4.00.1111 command.com MS-DOS Prompt 492x259.png|thumb|250px|command.com running in a [[Windows console]] on [[Windows 95]] (MS-DOS Prompt)]]
 
<code>'''COMMAND.COM'''</code> is the default [[command-line interpreter]] for [[MS-DOS]], [[Windows 95]], [[Windows 98]] and [[Windows Me]]. 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 [[Booting|boot]] ([[init process]]). As a shell, COMMAND.COM has two distinct modes of operation: [[Read-eval-print loop|interactive mode]] and [[Batch processing|batch mode]]. Internal commands are commands stored directly inside the COMMAND.COM [[Binary file|binary]]; thus, they are always available, but can only be executed directly from the command interpreter.{{Citation needed|date=March 2024}}
[[File:Microsoft Windows 95 Version 4.00.1111 command.com MS-DOS Prompt 492x259.png|thumb|250px|{{mono|COMMAND.COM}} running in a [[Windows console]] on [[Windows 95]] (MS-DOS Prompt)]]
'''{{mono|COMMAND.COM}}''' is the default [[command-line interpreter]] for [[MS-DOS]], [[Windows 95]], [[Windows 98]] and [[Windows Me]]. 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 [[Booting|boot]] ([[init process]]). As a shell, {{mono|COMMAND.COM}} has two distinct modes of operation: [[Read-eval-print loop|interactive mode]] and [[Batch processing|batch mode]]. Internal commands are commands stored directly inside the {{mono|COMMAND.COM}} [[Binary file|binary]]; thus, they are always available, but can only be executed directly from the command interpreter.{{Citation needed|date=March 2024}}


== Description ==
== Description ==
COMMAND.COM's successor on [[OS/2]] and [[Windows NT]] systems is [[cmd.exe]], although COMMAND.COM is available in [[virtual DOS machine]]s on [[IA-32]] versions of those operating systems as well. The {{Mono|COMMAND.COM}} filename was also used by {{ill|Disk Control Program|de|vertical-align=sup}} (DCP), an MS-DOS derivative by the former East German [[VEB Robotron]].<ref name="DCP_2016" />
{{mono|COMMAND.COM}}'s successor on [[OS/2]] and [[Windows NT]] systems is [[cmd.exe]], although COMMAND.COM is available in [[virtual DOS machine]]s on [[IA-32]] versions of those operating systems as well. The {{Mono|COMMAND.COM}} filename was also used by {{ill|Disk Control Program|de}} (DCP), an MS-DOS derivative by the former East German [[VEB Robotron]].<ref name="DCP_2016" />


COMMAND.COM is a DOS program. Programs launched from COMMAND.COM are DOS programs that use the [[DOS API]] to communicate with the disk operating system. The compatible command processor under [[FreeDOS]] is sometimes also called [[FreeCom]].
{{mono|COMMAND.COM}} is a DOS program. Programs launched from {{mono|COMMAND.COM}} are DOS programs that use the [[DOS API]] to communicate with the disk operating system. The compatible command processor under [[FreeDOS]] is sometimes also called [[FreeCom]].


==Operating modes==
==Operating modes==
As a shell, COMMAND.COM has two distinct modes of operation. The first is [[Read-eval-print loop|interactive mode]], in which the user types commands which are then executed immediately. The second is [[Batch processing|batch mode]], which executes a predefined sequence of commands stored as a text file with the [[Batch file|.BAT]] extension.
As a shell, {{mono|COMMAND.COM}} has two distinct modes of operation. The first is [[Read-eval-print loop|interactive mode]], in which the user types commands which are then executed immediately. The second is [[Batch processing|batch mode]], which executes a predefined sequence of commands stored as a text file with the [[Batch file|.BAT]] extension.


=={{anchor|Prompt}}Internal commands==
=={{anchor|Prompt}}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.
Internal commands are commands stored directly inside the {{mono|COMMAND.COM}} binary. Thus, they are always available but can only be executed directly from the command interpreter.


All commands are executed after the {{keypress|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.
All commands are executed after the {{keypress|Enter}} key is pressed at the end of the line. {{mono|COMMAND.COM}} is not case-sensitive, meaning commands can be typed in any mixture of upper and lower case.


; [[BREAK (DOS command)|BREAK]]: Controls the handling of program interruption with {{keypress|Ctrl|C}} or {{keypress|Ctrl|Break}}.
; [[BREAK (DOS command)|{{mono|BREAK}}]]: Controls the handling of program interruption with {{keypress|Ctrl|C}} or {{keypress|Ctrl|Break}}.
; [[CHCP (command)|CHCP]]: Displays or changes the current system [[code page]].
; [[CHCP (command)|{{mono|CHCP}}]]: Displays or changes the current system [[code page]].
; [[CHDIR|CHDIR, CD]]: Changes the current [[working directory]] or displays the current directory.
; [[CHDIR|{{mono|CHDIR}}, {{mono|CD}}]]: Changes the current [[working directory]] or displays the current directory.
; [[CLS (DOS command)|CLS]]: Clears the screen.
; [[CLS (DOS command)|{{mono|CLS}}]]: Clears the screen.
; [[COPY (DOS command)|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).
; [[COPY (DOS command)|{{mono|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).
; [[CTTY (DOS command)|CTTY]]: Defines the device to use for input and output.
; [[CTTY (DOS command)|{{mono|CTTY}}]]: Defines the device to use for input and output.
; [[DATE (command)|DATE]]: Display and set the date of the system.
; [[DATE (command)|{{mono|DATE}}]]: Display and set the date of the system.
; [[DEL (command)|DEL, ERASE]]: Deletes a file. When used on a directory, deletes all files inside the directory only. In comparison, the external command [[DELTREE]] deletes all subdirectories and files inside a directory as well as the directory itself.
; [[DEL (command)|{{mono|DEL}}, {{mono|ERASE}}]]: Deletes a file. When used on a directory, deletes all files inside the directory only. In comparison, the external command {{mono|[[DELTREE]]}} deletes all subdirectories and files inside a directory as well as the directory itself.
; [[DIR (command)|DIR]]: Lists the files in the specified directory.
; [[DIR (command)|{{mono|DIR}}]]: Lists the files in the specified directory.
; [[ECHO (command)|ECHO]]: Toggles whether text is displayed ({{codett|ECHO ON}}) or not ({{codett|ECHO OFF}}). Also displays text on the screen ({{codett|ECHO text}}).
; [[ECHO (command)|{{mono|ECHO}}]]: Toggles whether the commands executed by a [[batch file]] are displayed on screen ({{codett|ECHO ON}}) or not ({{codett|ECHO OFF}}). Also displays text on the screen ({{codett|ECHO text}}).
; [[EXIT (command)|EXIT]]: Exits from COMMAND.COM and returns to the program which launched it.
; [[EXIT (command)|{{mono|EXIT}}]]: Exits from {{mono|COMMAND.COM}} and returns to the program which launched it.
; [[LFNFOR]]: Enables or disables the return of [[long filename]]s by the FOR command. ([[Windows 9x]]).{{Citation needed|date=March 2024}}
; {{mono|[[LFNFOR]]}}: Enables or disables the return of [[long filename]]s by the {{mono|FOR}} command. ([[Windows 9x]]).{{Citation needed|date=March 2024}}
; [[LOADHIGH|LOADHIGH, LH]]: Loads a program into [[Upper Memory Area|upper memory]] ({{codett|HILOAD}} in [[DR DOS]]).
; [[LOADHIGH|{{mono|LOADHIGH}}, {{mono|LH}}]]: Loads a program into [[Upper Memory Area|upper memory]] ({{codett|HILOAD}} in [[DR DOS]]).
; [[LOCK (DOS command)|LOCK]]: Enables external programs to perform low-level disk access to a volume. ([[MS-DOS 7.1]] and [[Windows 9x]] only){{Citation needed|date=March 2024}}
; [[LOCK (DOS command)|{{mono|LOCK}}]]: Enables external programs to perform low-level disk access to a volume. ([[MS-DOS 7.1]] and [[Windows 9x]] only){{Citation needed|date=March 2024}}
; [[MKDIR|MKDIR, MD]]: Creates a new directory.
; [[MKDIR|{{mono|MKDIR}}, {{mono|MD}}]]: Creates a new directory.
; [[PATH (DOS command)|PATH]]: Displays or changes the value of the PATH [[environment variable]] which controls the places where COMMAND.COM will search for executable files.
; [[PATH (DOS command)|{{mono|PATH}}]]: Displays or changes the value of the {{mono|PATH}} [[environment variable]] which controls the places where {{mono|COMMAND.COM}} will search for executable files.
; [[PROMPT (DOS command)|PROMPT]]: Displays or change the value of the PROMPT environment variable which controls the appearance of the prompt.
; [[PROMPT (DOS command)|{{mono|PROMPT}}]]: Displays or change the value of the {{mono|PROMPT}} environment variable which controls the appearance of the prompt.
; [[REN (command)|RENAME, REN]]: Renames a file or directory.
; [[REN (command)|{{mono|RENAME}}, {{mono|REN}}]]: Renames a file or directory.
; [[RMDIR|RMDIR, RD]]: Removes an empty directory.
; [[RMDIR|{{mono|RMDIR}}, {{mono|RD}}]]: Removes an empty directory.
; [[SET (DOS command)|SET]]: Sets the value of an [[environment variable]]; without arguments, shows all defined environment variables.
; [[SET (DOS command)|{{mono|SET}}]]: Sets the value of an [[environment variable]]; without arguments, shows all defined environment variables.
; [[TIME (command)|TIME]]: Display and set the time of the system.
; [[TIME (command)|{{mono|TIME}}]]: Display and set the time of the system.
; [[TRUENAME]]: Display the fully expanded physical name of a file, resolving [[ASSIGN (DOS command)|ASSIGN]], [[JOIN (DOS command)|JOIN]] and [[SUBST]] logical filesystem mappings.<ref name="Paul_1997_NWDOSTIP"/>
; {{mono|[[TRUENAME]]}}: Display the fully expanded physical name of a file, resolving [[ASSIGN (DOS command)|{{mono|ASSIGN}}]], [[JOIN (DOS command)|{{mono|JOIN}}]] and [[SUBST]] logical filesystem mappings.<ref name="Paul_1997_NWDOSTIP"/>
; [[TYPE (DOS command)|TYPE]]: Display the content of a file on the console.
; [[TYPE (DOS command)|{{mono|TYPE}}]]: Display the content of a file on the console.
; [[UNLOCK (DOS command)|UNLOCK]]: Disables low-level disk access. (MS-DOS 7.1 and [[Windows 9x]] only){{Citation needed|date=March 2024}}
; [[UNLOCK (DOS command)|{{mono|UNLOCK}}]]: Disables low-level disk access. (MS-DOS 7.1 and [[Windows 9x]] only){{Citation needed|date=March 2024}}
; [[VER (command)|VER]]: Displays the version of the [[operating system]].
; [[VER (command)|{{mono|VER}}]]: Displays the version of the [[operating system]].
; [[VERIFY (DOS command)|VERIFY]]: Enable or disable verification of writing for files.
; [[VERIFY (DOS command)|{{mono|VERIFY}}]]: Enable or disable verification of writing for files.
; [[VOL (command)|VOL]]:Shows information about a volume.
; [[VOL (command)|{{mono|VOL}}]]: Shows information about a volume.


=== Batch file commands ===
=== Batch file commands ===
[[Control structure|Control structures]] are mostly used inside batch files, although they can also be used interactively.<ref name="Caldera_1998_USER_CH7" /><ref name="Paul_1997_NWDOSTIP" />
[[Control structure]]s are mostly used inside batch files, although they can also be used interactively.<ref name="Caldera_1998_USER_CH7" /><ref name="Paul_1997_NWDOSTIP" />


; <nowiki>:</nowiki>''label'': Defines a target for GOTO.
; {{mono|<nowiki>:</nowiki>}}''label'': Defines a target for {{mono|GOTO}}.
; [[CALL (DOS command)|CALL]]: Executes another batch file and returns to the old one and continues.
; [[CALL (DOS command)|{{mono|CALL}}]]: Executes another batch file and returns to the old one and continues.
; [[FOR (DOS command)|FOR]]: Iteration: repeats a command for each out of a specified set of files.
; [[FOR (DOS command)|{{mono|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 ({{codett|:likethis}}).
; {{mono|[[GOTO]]}}: Moves execution to a specified label. Labels are specified at the beginning of a line, with a colon ({{codett|:likethis}}).
; [[IF (DOS command)|IF]]: Conditional statement, allows branching of the program execution.
; [[IF (DOS command)|{{mono|IF}}]]: Conditional statement, allows branching of the program execution.
; [[PAUSE (DOS command)|PAUSE]]: Halts execution of the program and displays a message asking the user to press [[any key]] to continue.
; [[PAUSE (DOS command)|{{mono|PAUSE}}]]: Halts execution of the program and displays a message asking the user to press [[any key]] to continue.
; [[REM (DOS command)|REM]]: [[comment (computer programming)|comment]]: any text following this command is ignored.
; [[REM (DOS command)|{{mono|REM}}]]: [[comment (computer programming)|comment]]: any text following this command is ignored.
; [[SHIFT (DOS command)|SHIFT]]: Replaces each of the [[replacement parameter]]s with the subsequent one (e.g. {{codett|%0}} with {{codett|%1}}, {{codett|%1}} with {{codett|%2}}, etc.).
; [[SHIFT (DOS command)|{{mono|SHIFT}}]]: Replaces each of the [[replacement parameter]]s with the subsequent one (e.g. {{codett|%0}} with {{codett|%1}}, {{codett|%1}} with {{codett|%2}}, etc.).


==== IF command ====
==== IF command ====
On exit, all external commands submit a [[return code]] (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).<ref name="Paul_1997_BATTIPS"/><ref name="FD_2003_Errorlevel"/><ref name="Paul_2003_Exitcodes"/><ref name="Allen_2005"/>
On exit, all external commands submit a [[return code]] (a value between {{mono|0}} and {{mono|255}}) to the calling program. Most programs have a certain convention for their return codes (for instance, 0 for a successful execution).<ref name="Paul_1997_BATTIPS"/><ref name="FD_2003_Errorlevel"/><ref name="Paul_2003_Exitcodes"/><ref name="Allen_2005"/>


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.{{Citation needed|date=March 2024}}
If a program was invoked by {{mono|COMMAND.COM}}, the internal IF command with its {{mono|ERRORLEVEL}} conditional can be used to test on error conditions of the last invoked external program.{{Citation needed|date=March 2024}}


Under COMMAND.COM, internal commands do not establish a new value.{{Citation needed|date=March 2024}}
Under {{mono|COMMAND.COM}}, internal commands do not establish a new value.{{Citation needed|date=March 2024}}


==Variables==
==Variables==
Batch files for COMMAND.COM can have four kinds of variables:
Batch files for {{mono|COMMAND.COM}} can have four kinds of variables:
* [[Environment variable]]s: These have the {{mono|%VARIABLE%}} 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.{{citation needed|date=August 2017}}
* [[Environment variable]]s: These have the {{mono|%VARIABLE%}} form and are associated with values with the SET statement. Before DOS 3 {{mono|COMMAND.COM}} will only expand environment variables in batch mode; that is, not interactively at the command prompt.{{citation needed|date=August 2017}}
* [[Replacement parameter]]s: These have the form {{mono|%0}}, {{mono|%1}}...{{mono|%9}}, and initially contain the command name and the first nine [[command-line parameter]]s passed to the script (e.g., if the invoking command was {{kbd|myscript.bat John Doe}}, then {{mono|%0}} is "myscript.bat", {{mono|%1}} is "John" and {{mono|%2}} is "Doe").  The parameters to the right of the ninth can be mapped into range by using the SHIFT statement.{{Citation needed|date=March 2024}}
* [[Replacement parameter]]s: These have the form {{mono|%0}}, {{mono|%1}}...{{mono|%9}}, and initially contain the command name and the first nine [[command-line parameter]]s passed to the script (e.g., if the invoking command was {{kbd|myscript.bat John Doe}}, then {{mono|%0}} is {{mono|"myscript.bat"}}, {{mono|%1}} is {{mono|"John"}} and {{mono|%2}} is {{mono|"Doe"}}).  The parameters to the right of the ninth can be mapped into range by using the SHIFT statement.{{Citation needed|date=March 2024}}
* Loop variables: Used in loops, they have the {{mono|%%a}} 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.{{Citation needed|date=March 2024}}
* Loop variables: Used in loops, they have the {{mono|%%a}} 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.{{Citation needed|date=March 2024}}
* Under [[Novell DOS 7]]<!-- 1993 -->, [[OpenDOS 7.01]], [[DR-DOS 7.02]] and higher, COMMAND.COM also supports a number of [[system information variable]]s,<ref name="Caldera_1998_USER_CH7"/><ref name="Caldera_1998_USER"/><ref name="Paul_1997_NWDOSTIP"/> a feature earlier found in [[4DOS 3.00]]<!-- 1990 --> and higher<ref name="4DOS_8.00_HELP"/> as well as in [[Multiuser DOS]],<!-- 1991 --><ref name="Paul_1997_NWDOSTIP"/><!-- not in CDOS 386 1.0 (1987), not sure about CDOS 386 3.0 (1989) --> although most of the supported variable names differ.
* Under [[Novell DOS 7]]<!-- 1993 -->, [[OpenDOS 7.01]], [[DR-DOS 7.02]] and higher, {{mono|COMMAND.COM}} also supports a number of [[system information variable]]s,<ref name="Caldera_1998_USER_CH7"/><ref name="Caldera_1998_USER"/><ref name="Paul_1997_NWDOSTIP"/> a feature earlier found in [[4DOS 3.00]]<!-- 1990 --> and higher<ref name="4DOS_8.00_HELP"/> as well as in [[Multiuser DOS]],<!-- 1991 --><ref name="Paul_1997_NWDOSTIP"/><!-- not in CDOS 386 1.0 (1987), not sure about CDOS 386 3.0 (1989) --> although most of the supported variable names differ.


==Redirection, piping, and chaining==
==Redirection, piping, and chaining==
Because DOS is a single-tasking operating system, [[Pipeline (software)|piping]] is achieved by running commands sequentially, redirecting to and from a [[temporary file]].{{Citation needed|date=March 2024}} COMMAND.COM makes no provision for redirecting the [[Standard streams#Standard error (stderr)|standard error]] channel.{{Citation needed|date=March 2024}}
Because DOS is a single-tasking operating system, [[Pipeline (software)|piping]] is achieved by running commands sequentially, redirecting to and from a [[temporary file]].{{Citation needed|date=March 2024}} {{mono|COMMAND.COM}} makes no provision for redirecting the [[Standard streams#Standard error (stderr)|standard error]] channel.{{Citation needed|date=March 2024}}


; <code>''command'' < ''filename''</code> : Redirect [[Standard streams#Standard input (stdin)|standard input]] from a file or device
; <code>''command'' < ''filename''</code> : Redirect [[Standard streams#Standard input (stdin)|standard input]] from a file or device
Line 95: Line 97:
; <code>''command1'' | ''command2''</code> : Pipe [[Standard streams#Standard output (stdout)|standard output]] from ''command1'' to [[Standard streams#Standard input (stdin)|standard input]] of ''command2''
; <code>''command1'' | ''command2''</code> : Pipe [[Standard streams#Standard output (stdout)|standard output]] from ''command1'' to [[Standard streams#Standard input (stdin)|standard input]] of ''command2''
; <code>''command1'' ¶ ''command2''</code> :
; <code>''command1'' ¶ ''command2''</code> :
: Commands separated by ASCII-20 (¶, invoked by {{keypress|Ctrl|T}}) are executed in sequence (chaining of commands).<ref name="Paul_1997_NWDOSTIP"/> In other words, first ''command1'' is executed until termination, then ''command2''.<ref name="Paul_1997_NWDOSTIP"/> This is an undocumented feature in COMMAND.COM of [[MS-DOS 5.0|MS-DOS]]/[[PC DOS 5.0]]<!-- tested MS-DOS 6.2 and PC DOS 7 --> and higher.<ref name="Paul_1997_NWDOSTIP"/> It is also supported by COMMAND.COM<!-- but not by CMD --> of the Windows NT family<!-- tested Windows XP --> as well as by DR-DOS 7.07. All versions of DR-DOS COMMAND.COM<!-- since 3.xx --> already supported a similar internal function utilizing an exclamation mark (!) instead (a feature originally derived from [[Concurrent DOS]] and [[Multiuser DOS]]) - in the single-user line this feature was only available internally (in built-in startup scripts like "!DATE!TIME") and indirectly through [[DOSKEY]]'s $T parameter to avoid problems with ! as a valid filename character.<ref name="Paul_1997_NWDOSTIP"/> [[4DOS]] supports a configurable command line separator ([[4DOS.INI]] CommandSep= or SETDOS /C), which defaults to ^.<ref name="4DOS_8.00_HELP"/> COMMAND.COM in newer versions of Windows NT<!-- works for example in XP, but not in MS-DOS/PC DOS COMMAND.COM --> also supports an {{code|&}} separator for compatibility with the cmd syntax in OS/2 and the Windows NT family.<ref name="4DOS_8.00_HELP"/> (cmd does not support the ¶ separator.)
: Commands separated by ASCII-20 (¶, invoked by {{keypress|Ctrl|T}}) are executed in sequence (chaining of commands).<ref name="Paul_1997_NWDOSTIP"/> In other words, first ''command1'' is executed until termination, then ''command2''.<ref name="Paul_1997_NWDOSTIP"/> This is an undocumented feature in {{mono|COMMAND.COM}} of [[MS-DOS 5.0|MS-DOS]]/[[PC DOS 5.0]]<!-- tested MS-DOS 6.2 and PC DOS 7 --> and higher.<ref name="Paul_1997_NWDOSTIP"/> It is also supported by {{mono|COMMAND.COM}}<!-- but not by CMD --> of the Windows NT family<!-- tested Windows XP --> as well as by DR-DOS 7.07. All versions of DR-DOS {{mono|COMMAND.COM}}<!-- since 3.xx --> already supported a similar internal function utilizing an exclamation mark (!) instead (a feature originally derived from [[Concurrent DOS]] and [[Multiuser DOS]]) - in the single-user line this feature was only available internally (in built-in startup scripts like "!DATE!TIME") and indirectly through [[DOSKEY]]'s $T parameter to avoid problems with ! as a valid filename character.<ref name="Paul_1997_NWDOSTIP"/> [[4DOS]] supports a configurable command line separator ([[4DOS.INI]] CommandSep= or SETDOS /C), which defaults to ^.<ref name="4DOS_8.00_HELP"/> {{mono|COMMAND.COM}} in newer versions of Windows NT<!-- works for example in XP, but not in MS-DOS/PC DOS {{mono|COMMAND.COM}} --> also supports an {{code|&}} separator for compatibility with the cmd syntax in OS/2 and the Windows NT family.<ref name="4DOS_8.00_HELP"/> (cmd does not support the ¶ separator.)


==Limitations==
==Limitations==
Line 102: Line 104:
==In popular culture==
==In popular culture==


* The message "Loading COMMAND.COM" can be seen on a [[Head-Up Display|HUD]] view of the [[T-800|Terminator]] and the internal viewport of [[RoboCop]] when he reboots.{{Citation needed|date=March 2024}}
* The message "Loading {{mono|COMMAND.COM}}" can be seen on a [[Head-Up Display|HUD]] view of the [[T-800|Terminator]] and the internal viewport of [[RoboCop]] when he reboots.{{Citation needed|date=March 2024}}
* In the animated children's TV series ''[[ReBoot]]'', which takes place inside computers, the leader of a system (the equivalent of a city) is called the COMMAND.COM.{{Citation needed|date=March 2024}}
* In the animated children's TV series ''[[ReBoot]]'', which takes place inside computers, the leader of a system (the equivalent of a city) is called the {{mono|COMMAND.COM}}.<ref name=filmcomment>{{cite news | last=Murphy|first= Kathleen | title=Cyberscreens | publisher= [[Film Comment]] via Inwap.com| pages=38–43 | date= July–August 1995| url=http://www.inwap.com/mf/reboot/Press.html|access-date= July 26, 2015 | archive-url = https://web.archive.org/web/20150612094706/http://www.inwap.com/mf/reboot/Press.html | archive-date= June 12, 2015 | url-status=live}}</ref>


==See also==
==See also==
Line 112: Line 114:
* {{hlist|class=inline|[[IBMBIO.COM]] | [[IO.SYS]]}} — starts the command processor as the first process
* {{hlist|class=inline|[[IBMBIO.COM]] | [[IO.SYS]]}} — starts the command processor as the first process
* [[SHELL (CONFIG.SYS directive)]] — to override default command processor
* [[SHELL (CONFIG.SYS directive)]] — to override default command processor
* [[COMSPEC (environment variable)]] — set by COMMAND.COM to reload transient portion of itself
* [[COMSPEC (environment variable)]] — set by {{mono|COMMAND.COM}} to reload transient portion of itself
* [[CMDLINE (environment variable)]] — set by COMMAND.COM to pass long command lines to external programs
* [[CMDLINE (environment variable)]] — set by COMMAND.COM to pass long command lines to external programs
* {{hlist|class=inline|[[4DOS]] | [[NDOS]]}} — third-party replacement command processors
* {{hlist|class=inline|[[4DOS]] | [[NDOS]]}} — third-party replacement command processors
* [[DOSSHELL]] / [[ViewMAX]] — alternative DOS shells
* [[DOSSHELL]] / [[ViewMAX]] — alternative DOS shells
<!-- * [[TASKMAX]] / [[TASKMGR]] — instances daughter processes -->
<!-- * [[TASKMAX]] / [[TASKMGR]] — instances daughter processes -->
* {{hlist|class=inline|[[Concurrent DOS]] | [[Multiuser DOS]] | [[REAL/32]]}} — have similar command processors not named COMMAND.COM
* {{hlist|class=inline|[[Concurrent DOS]] | [[Multiuser DOS]] | [[REAL/32]]}} — have similar command processors not named {{mono|COMMAND.COM}}
* [[PC-MOS/386]] — has a similar command processor also named COMMAND.COM
* [[PC-MOS/386]] — has a similar command processor also named {{mono|COMMAND.COM}}
* [[Transient Program Area]] — memory available for use either by the running application or the transient portion of COMMAND.COM
* [[Transient Program Area]] — memory available for use either by the running application or the transient portion of {{mono|COMMAND.COM}}
* [[SpartaDOS X]] — a similar implementation for Atari computers
* [[SpartaDOS X]] — a similar implementation for Atari computers
* [[PowerShell]]


==References==
==References==
Line 132: Line 135:
<ref name="Caldera_1998_USER_CH7">{{cite book |title=Caldera DR-DOS 7.02 User Guide |publisher=[[Caldera, Inc.]] |date=1998 |orig-year=1993, 1997 |chapter=Chapter 7: Batch Processing |chapter-url=http://www.drdos.net/documentation/usergeng/07ugch7.htm |access-date=2017-09-11 |url-status=dead |archive-url=https://web.archive.org/web/20170911163945/http://www.drdos.net/documentation/usergeng/07ugch7.htm |archive-date=2017-09-11}}</ref>
<ref name="Caldera_1998_USER_CH7">{{cite book |title=Caldera DR-DOS 7.02 User Guide |publisher=[[Caldera, Inc.]] |date=1998 |orig-year=1993, 1997 |chapter=Chapter 7: Batch Processing |chapter-url=http://www.drdos.net/documentation/usergeng/07ugch7.htm |access-date=2017-09-11 |url-status=dead |archive-url=https://web.archive.org/web/20170911163945/http://www.drdos.net/documentation/usergeng/07ugch7.htm |archive-date=2017-09-11}}</ref>
<ref name="Paul_1997_MSDOS">{{cite book |title=MSDOSTIPs — Tips für den Umgang mit MS-DOS 5.0-7 |publisher=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-01 |orig-year=1994-01-01 |language=de |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/msdostip.htm |access-date=2013-10-25 |url-status=live |archive-url=https://web.archive.org/web/20170822214030/http://www.antonis.de/dos/dos-tuts/mpdostip/html/msdostip.htm |archive-date=2017-08-22}} (NB. MSDOSTIP.TXT is part of MPDOSTIP.ZIP, maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the MSDOSTIP.TXT file.) [https://web.archive.org/web/20190601152204/https://www.sac.sk/download/text/mpdostip.zip<!-- A yet older version 155 from 1997-05-13 of the 1997-07-15 distribution archive. -->]</ref>
<ref name="Paul_1997_MSDOS">{{cite book |title=MSDOSTIPs — Tips für den Umgang mit MS-DOS 5.0-7 |publisher=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-01 |orig-year=1994-01-01 |language=de |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/msdostip.htm |access-date=2013-10-25 |url-status=live |archive-url=https://web.archive.org/web/20170822214030/http://www.antonis.de/dos/dos-tuts/mpdostip/html/msdostip.htm |archive-date=2017-08-22}} (NB. MSDOSTIP.TXT is part of MPDOSTIP.ZIP, maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the MSDOSTIP.TXT file.) [https://web.archive.org/web/20190601152204/https://www.sac.sk/download/text/mpdostip.zip<!-- A yet older version 155 from 1997-05-13 of the 1997-07-15 distribution archive. -->]</ref>
<ref name="4DOS_8.00_HELP">{{quote|source={{cite book |title=4DOS 8.00 online help |title-link=4DOS 8.00 |author-first1=Hardin |author-last1=Brothers |author-first2=Tom |author-last2=Rawson |author-link2=Tom Rawson |author-first3=Rex C. |author-last3=Conn |author-link3=Rex C. Conn |author-first4=Matthias R. |author-last4=Paul |author-first5=Charles E. |author-last5=Dye |author-first6=Luchezar I. |author-last6=Georgiev |date=2002-02-27}} |text=[...] Multiple Commands: You can type several commands on the same command line, separated by a caret [^]. For example, if you know you want to copy all of your .TXT files to drive A: and then run CHKDSK to be sure that drive A's file structure is in good shape, you could enter the following command: {{code|C:\>COPY *.TXT A: ^ CHKDSK A:|doscon}} You may put as many commands on the command line as you wish, as long as the total length of the command line does not exceed 511 characters. You can use multiple commands in aliases and batch files as well as at the command line. If you don't like using the default command separator, you can pick another character using the {{code|SETDOS /C}} command or the CommandSep directive in [[4DOS.INI]]. [...] {{code|SETDOS /C:}} (Compound character) This option sets the character used for separating multiple commands on the same line. The default is the caret [^]. You cannot use any of the redirection characters [<>{{!}}], or the blank, tab, comma, or equal sign as the command separator. The command separator is saved by SETLOCAL and restored by ENDLOCAL. This example changes the separator to a tilde [~]: {{code|C:\>SETDOS /C~|doscon}} (You can specify either the character itself, or its ASCII code as a decimal number, or a hexadecimal number preceded by 0x.) [...] CommandSep = c (^): This is the character used to separate multiple commands on the same line. [...] Special Character Compatibility: If you use two or more of our products, or if you want to share aliases and batch files with users of different products, you need to be aware of the differences in three important characters: the Command Separator [...], the Escape Character [...], and the Parameter Character [...]. The default values of each of these characters in each product is shown in the following chart: [...] Product, Separator, Escape Parameter [...] 4DOS: ^, ↑, & [...] 4OS2, 4NT, Take Command: &, ^, $ [...] (The up-arrow [↑] represents the ASCII Ctrl-X character, numeric value 24.) [...]}}</ref>
<ref name="4DOS_8.00_HELP">{{blockquote|source={{cite book |title=4DOS 8.00 online help |title-link=4DOS 8.00 |author-first1=Hardin |author-last1=Brothers |author-first2=Tom |author-last2=Rawson |author-link2=Tom Rawson |author-first3=Rex C. |author-last3=Conn |author-link3=Rex C. Conn |author-first4=Matthias R. |author-last4=Paul |author-first5=Charles E. |author-last5=Dye |author-first6=Luchezar I. |author-last6=Georgiev |date=2002-02-27}} |text=[...] Multiple Commands: You can type several commands on the same command line, separated by a caret [^]. For example, if you know you want to copy all of your .TXT files to drive A: and then run CHKDSK to be sure that drive A's file structure is in good shape, you could enter the following command: {{code|C:\>COPY *.TXT A: ^ CHKDSK A:|doscon}} You may put as many commands on the command line as you wish, as long as the total length of the command line does not exceed 511 characters. You can use multiple commands in aliases and batch files as well as at the command line. If you don't like using the default command separator, you can pick another character using the {{code|SETDOS /C}} command or the CommandSep directive in [[4DOS.INI]]. [...] {{code|SETDOS /C:}} (Compound character) This option sets the character used for separating multiple commands on the same line. The default is the caret [^]. You cannot use any of the redirection characters [<>{{!}}], or the blank, tab, comma, or equal sign as the command separator. The command separator is saved by SETLOCAL and restored by ENDLOCAL. This example changes the separator to a tilde [~]: {{code|C:\>SETDOS /C~|doscon}} (You can specify either the character itself, or its ASCII code as a decimal number, or a hexadecimal number preceded by 0x.) [...] CommandSep = c (^): This is the character used to separate multiple commands on the same line. [...] Special Character Compatibility: If you use two or more of our products, or if you want to share aliases and batch files with users of different products, you need to be aware of the differences in three important characters: the Command Separator [...], the Escape Character [...], and the Parameter Character [...]. The default values of each of these characters in each product is shown in the following chart: [...] Product, Separator, Escape Parameter [...] 4DOS: ^, ↑, & [...] 4OS2, 4NT, Take Command: &, ^, $ [...] (The up-arrow [↑] represents the ASCII Ctrl-X character, numeric value 24.) [...]}}</ref>
<ref name="Paul_1997_NWDOSTIP">{{cite book |title=NWDOS-TIPs — Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds |publisher=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-30 |orig-year=1994-05-01 |edition=3 |version=Release 157 |language=de |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |access-date=2014-08-06 |url-status=dead |archive-url=https://web.archive.org/web/20161104235829/http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |archive-date=4 November 2016 }} (NB. The provided link points to a HTML-converted version of the {{code|NWDOSTIP.TXT}}, which is part of the {{code|MPDOSTIP.ZIP}}<!-- still named TIPS_MP.ZIP between 1991 and 1996-11 --> collection.) [https://web.archive.org/web/20190601152204/https://www.sac.sk/download/text/mpdostip.zip<!-- A yet older version 155 from 1997-05-13 of the 1997-07-15 distribution archive. -->]</ref>
<ref name="Paul_1997_NWDOSTIP">{{cite book |title=NWDOS-TIPs — Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds |publisher=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-30 |orig-year=1994-05-01 |edition=3 |version=Release 157 |language=de |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |access-date=2014-08-06 |url-status=dead |archive-url=https://web.archive.org/web/20161104235829/http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |archive-date=4 November 2016 }} (NB. The provided link points to a HTML-converted version of the {{code|NWDOSTIP.TXT}}, which is part of the {{code|MPDOSTIP.ZIP}}<!-- still named TIPS_MP.ZIP between 1991 and 1996-11 --> collection.) [https://web.archive.org/web/20190601152204/https://www.sac.sk/download/text/mpdostip.zip<!-- A yet older version 155 from 1997-05-13 of the 1997-07-15 distribution archive. -->]</ref>
<ref name="DCP_2016">{{cite web |title=Betriebssystem DCP |author-first1=Rüdiger |author-last1=Kurth |author-first2=Martin |author-last2=Groß |author-first3=Henry |author-last3=Hunger |date=2016-11-29 |orig-year=2007 |language=de |website=www.robotrontechnik.de |url=http://www.robotrontechnik.de/html/software/dcp.htm |access-date=2019-04-28 |url-status=live |archive-url=https://web.archive.org/web/20190403061152/http://www.robotrontechnik.de/html/software/dcp.htm |archive-date=2019-04-03}}</ref>
<ref name="DCP_2016">{{cite web |title=Betriebssystem DCP |author-first1=Rüdiger |author-last1=Kurth |author-first2=Martin |author-last2=Groß |author-first3=Henry |author-last3=Hunger |date=2016-11-29 |orig-year=2007 |language=de |website=www.robotrontechnik.de |url=http://www.robotrontechnik.de/html/software/dcp.htm |access-date=2019-04-28 |url-status=live |archive-url=https://web.archive.org/web/20190403061152/http://www.robotrontechnik.de/html/software/dcp.htm |archive-date=2019-04-03}}</ref>

Latest revision as of 06:20, 19 December 2025

Template:Short description Script error: No such module "redirect hatnote". Script error: No such module "Distinguish". Template:Use list-defined references Script error: No such module "Unsubst". Template:Use dmy dates Script error: No such module "Infobox".Template:Template other Script error: No such module "Check for unknown parameters".Script error: No such module "Check for conflicting parameters".

File:Microsoft Windows 95 Version 4.00.1111 command.com MS-DOS Prompt 492x259.png
<templatestyles src="Mono/styles.css" />COMMAND.COM running in a Windows console on Windows 95 (MS-DOS Prompt)

<templatestyles src="Mono/styles.css" />COMMAND.COM is the default command-line interpreter for MS-DOS, Windows 95, Windows 98 and Windows Me. 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). As a shell, <templatestyles src="Mono/styles.css" />COMMAND.COM has two distinct modes of operation: interactive mode and batch mode. Internal commands are commands stored directly inside the <templatestyles src="Mono/styles.css" />COMMAND.COM binary; thus, they are always available, but can only be executed directly from the command interpreter.Script error: No such module "Unsubst".

Description

<templatestyles src="Mono/styles.css" />COMMAND.COM's successor on OS/2 and Windows NT systems is cmd.exe, although COMMAND.COM is available in virtual DOS machines on IA-32 versions of those operating systems as well. The <templatestyles src="Mono/styles.css" />COMMAND.COM filename was also used by Template:Ill (DCP), an MS-DOS derivative by the former East German VEB Robotron.[1]

<templatestyles src="Mono/styles.css" />COMMAND.COM is a DOS program. Programs launched from <templatestyles src="Mono/styles.css" />COMMAND.COM are DOS programs that use the DOS API to communicate with the disk operating system. The compatible command processor under FreeDOS is sometimes also called FreeCom.

Operating modes

As a shell, <templatestyles src="Mono/styles.css" />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, which executes a predefined sequence of commands stored as a text file with the .BAT extension.

Script error: No such module "anchor".Internal commands

Internal commands are commands stored directly inside the <templatestyles src="Mono/styles.css" />COMMAND.COM binary. Thus, they are always available but can only be executed directly from the command interpreter.

All commands are executed after the Template:Keypress key is pressed at the end of the line. <templatestyles src="Mono/styles.css" />COMMAND.COM is not case-sensitive, meaning commands can be typed in any mixture of upper and lower case.

<templatestyles src="Mono/styles.css" />BREAK
Controls the handling of program interruption with Template:Keypress or Template:Keypress.
<templatestyles src="Mono/styles.css" />CHCP
Displays or changes the current system code page.
<templatestyles src="Mono/styles.css" />CHDIR, <templatestyles src="Mono/styles.css" />CD
Changes the current working directory or displays the current directory.
<templatestyles src="Mono/styles.css" />CLS
Clears the screen.
<templatestyles src="Mono/styles.css" />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).
<templatestyles src="Mono/styles.css" />CTTY
Defines the device to use for input and output.
<templatestyles src="Mono/styles.css" />DATE
Display and set the date of the system.
<templatestyles src="Mono/styles.css" />DEL, <templatestyles src="Mono/styles.css" />ERASE
Deletes a file. When used on a directory, deletes all files inside the directory only. In comparison, the external command <templatestyles src="Mono/styles.css" />DELTREE deletes all subdirectories and files inside a directory as well as the directory itself.
<templatestyles src="Mono/styles.css" />DIR
Lists the files in the specified directory.
<templatestyles src="Mono/styles.css" />ECHO
Toggles whether the commands executed by a batch file are displayed on screen (Template:Codett) or not (Template:Codett). Also displays text on the screen (Template:Codett).
<templatestyles src="Mono/styles.css" />EXIT
Exits from <templatestyles src="Mono/styles.css" />COMMAND.COM and returns to the program which launched it.
<templatestyles src="Mono/styles.css" />LFNFOR
Enables or disables the return of long filenames by the <templatestyles src="Mono/styles.css" />FOR command. (Windows 9x).Script error: No such module "Unsubst".
<templatestyles src="Mono/styles.css" />LOADHIGH, <templatestyles src="Mono/styles.css" />LH
Loads a program into upper memory (Template:Codett in DR DOS).
<templatestyles src="Mono/styles.css" />LOCK
Enables external programs to perform low-level disk access to a volume. (MS-DOS 7.1 and Windows 9x only)Script error: No such module "Unsubst".
<templatestyles src="Mono/styles.css" />MKDIR, <templatestyles src="Mono/styles.css" />MD
Creates a new directory.
<templatestyles src="Mono/styles.css" />PATH
Displays or changes the value of the <templatestyles src="Mono/styles.css" />PATH environment variable which controls the places where <templatestyles src="Mono/styles.css" />COMMAND.COM will search for executable files.
<templatestyles src="Mono/styles.css" />PROMPT
Displays or change the value of the <templatestyles src="Mono/styles.css" />PROMPT environment variable which controls the appearance of the prompt.
<templatestyles src="Mono/styles.css" />RENAME, <templatestyles src="Mono/styles.css" />REN
Renames a file or directory.
<templatestyles src="Mono/styles.css" />RMDIR, <templatestyles src="Mono/styles.css" />RD
Removes an empty directory.
<templatestyles src="Mono/styles.css" />SET
Sets the value of an environment variable; without arguments, shows all defined environment variables.
<templatestyles src="Mono/styles.css" />TIME
Display and set the time of the system.
<templatestyles src="Mono/styles.css" />TRUENAME
Display the fully expanded physical name of a file, resolving <templatestyles src="Mono/styles.css" />ASSIGN, <templatestyles src="Mono/styles.css" />JOIN and SUBST logical filesystem mappings.[2]
<templatestyles src="Mono/styles.css" />TYPE
Display the content of a file on the console.
<templatestyles src="Mono/styles.css" />UNLOCK
Disables low-level disk access. (MS-DOS 7.1 and Windows 9x only)Script error: No such module "Unsubst".
<templatestyles src="Mono/styles.css" />VER
Displays the version of the operating system.
<templatestyles src="Mono/styles.css" />VERIFY
Enable or disable verification of writing for files.
<templatestyles src="Mono/styles.css" />VOL
Shows information about a volume.

Batch file commands

Control structures are mostly used inside batch files, although they can also be used interactively.[3][2]

<templatestyles src="Mono/styles.css" />:label
Defines a target for <templatestyles src="Mono/styles.css" />GOTO.
<templatestyles src="Mono/styles.css" />CALL
Executes another batch file and returns to the old one and continues.
<templatestyles src="Mono/styles.css" />FOR
Iteration: repeats a command for each out of a specified set of files.
<templatestyles src="Mono/styles.css" />GOTO
Moves execution to a specified label. Labels are specified at the beginning of a line, with a colon (Template:Codett).
<templatestyles src="Mono/styles.css" />IF
Conditional statement, allows branching of the program execution.
<templatestyles src="Mono/styles.css" />PAUSE
Halts execution of the program and displays a message asking the user to press any key to continue.
<templatestyles src="Mono/styles.css" />REM
comment: any text following this command is ignored.
<templatestyles src="Mono/styles.css" />SHIFT
Replaces each of the replacement parameters with the subsequent one (e.g. Template:Codett with Template:Codett, Template:Codett with Template:Codett, etc.).

IF command

On exit, all external commands submit a return code (a value between <templatestyles src="Mono/styles.css" />0 and <templatestyles src="Mono/styles.css" />255) to the calling program. Most programs have a certain convention for their return codes (for instance, 0 for a successful execution).[4][5][6][7]

If a program was invoked by <templatestyles src="Mono/styles.css" />COMMAND.COM, the internal IF command with its <templatestyles src="Mono/styles.css" />ERRORLEVEL conditional can be used to test on error conditions of the last invoked external program.Script error: No such module "Unsubst".

Under <templatestyles src="Mono/styles.css" />COMMAND.COM, internal commands do not establish a new value.Script error: No such module "Unsubst".

Variables

Batch files for <templatestyles src="Mono/styles.css" />COMMAND.COM can have four kinds of variables:

  • Environment variables: These have the <templatestyles src="Mono/styles.css" />%VARIABLE% form and are associated with values with the SET statement. Before DOS 3 <templatestyles src="Mono/styles.css" />COMMAND.COM will only expand environment variables in batch mode; that is, not interactively at the command prompt.Script error: No such module "Unsubst".
  • Replacement parameters: These have the form <templatestyles src="Mono/styles.css" />%0, <templatestyles src="Mono/styles.css" />%1...<templatestyles src="Mono/styles.css" />%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 Template:Kbd, then <templatestyles src="Mono/styles.css" />%0 is <templatestyles src="Mono/styles.css" />"myscript.bat", <templatestyles src="Mono/styles.css" />%1 is <templatestyles src="Mono/styles.css" />"John" and <templatestyles src="Mono/styles.css" />%2 is <templatestyles src="Mono/styles.css" />"Doe"). The parameters to the right of the ninth can be mapped into range by using the SHIFT statement.Script error: No such module "Unsubst".
  • Loop variables: Used in loops, they have the <templatestyles src="Mono/styles.css" />%%a 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.Script error: No such module "Unsubst".
  • Under Novell DOS 7, OpenDOS 7.01, DR-DOS 7.02 and higher, <templatestyles src="Mono/styles.css" />COMMAND.COM also supports a number of system information variables,[3][8][2] a feature earlier found in 4DOS 3.00 and higher[9] as well as in Multiuser DOS,[2] although most of the supported variable names differ.

Redirection, piping, and chaining

Because DOS is a single-tasking operating system, piping is achieved by running commands sequentially, redirecting to and from a temporary file.Script error: No such module "Unsubst". <templatestyles src="Mono/styles.css" />COMMAND.COM makes no provision for redirecting the standard error channel.Script error: No such module "Unsubst".

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
command1command2
Commands separated by ASCII-20 (¶, invoked by Template:Keypress) are executed in sequence (chaining of commands).[2] In other words, first command1 is executed until termination, then command2.[2] This is an undocumented feature in <templatestyles src="Mono/styles.css" />COMMAND.COM of MS-DOS/PC DOS 5.0 and higher.[2] It is also supported by <templatestyles src="Mono/styles.css" />COMMAND.COM of the Windows NT family as well as by DR-DOS 7.07. All versions of DR-DOS <templatestyles src="Mono/styles.css" />COMMAND.COM already supported a similar internal function utilizing an exclamation mark (!) instead (a feature originally derived from Concurrent DOS and Multiuser DOS) - in the single-user line this feature was only available internally (in built-in startup scripts like "!DATE!TIME") and indirectly through DOSKEY's $T parameter to avoid problems with ! as a valid filename character.[2] 4DOS supports a configurable command line separator (4DOS.INI CommandSep= or SETDOS /C), which defaults to ^.[9] <templatestyles src="Mono/styles.css" />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.[9] (cmd does not support the ¶ separator.)

Limitations

Generally, the command line length in interactive mode is limited to 126 characters.[10][11][12] In MS-DOS 6.22, the command line length in interactive mode is limited to 127 characters.Script error: No such module "Unsubst".

In popular culture

  • The message "Loading <templatestyles src="Mono/styles.css" />COMMAND.COM" can be seen on a HUD view of the Terminator and the internal viewport of RoboCop when he reboots.Script error: No such module "Unsubst".
  • In the animated children's TV series ReBoot, which takes place inside computers, the leader of a system (the equivalent of a city) is called the <templatestyles src="Mono/styles.css" />COMMAND.COM.[13]

See also

References

<templatestyles src="Reflist/styles.css" />

  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ a b c d e f g h Script error: No such module "citation/CS1". (NB. The provided link points to a HTML-converted version of the NWDOSTIP.TXT, which is part of the MPDOSTIP.ZIP collection.) [1]
  3. ↑ a b Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1". (NB. BATTIPS.TXT is part of MPDOSTIP.ZIP. The provided link points to an HTML-converted older version of the BATTIPS.TXT file.) [2]
  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1". [3]
  7. ↑ Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ a b c <templatestyles src="Template:Blockquote/styles.css" />

    [...] Multiple Commands: You can type several commands on the same command line, separated by a caret [^]. For example, if you know you want to copy all of your .TXT files to drive A: and then run CHKDSK to be sure that drive A's file structure is in good shape, you could enter the following command: C:\>COPY *.TXT A: ^ CHKDSK A: You may put as many commands on the command line as you wish, as long as the total length of the command line does not exceed 511 characters. You can use multiple commands in aliases and batch files as well as at the command line. If you don't like using the default command separator, you can pick another character using the SETDOS /C command or the CommandSep directive in 4DOS.INI. [...] SETDOS /C: (Compound character) This option sets the character used for separating multiple commands on the same line. The default is the caret [^]. You cannot use any of the redirection characters [<>|], or the blank, tab, comma, or equal sign as the command separator. The command separator is saved by SETLOCAL and restored by ENDLOCAL. This example changes the separator to a tilde [~]: C:\>SETDOS /C~ (You can specify either the character itself, or its ASCII code as a decimal number, or a hexadecimal number preceded by 0x.) [...] CommandSep = c (^): This is the character used to separate multiple commands on the same line. [...] Special Character Compatibility: If you use two or more of our products, or if you want to share aliases and batch files with users of different products, you need to be aware of the differences in three important characters: the Command Separator [...], the Escape Character [...], and the Parameter Character [...]. The default values of each of these characters in each product is shown in the following chart: [...] Product, Separator, Escape Parameter [...] 4DOS: ^, ↑, & [...] 4OS2, 4NT, Take Command: &, ^, $ [...] (The up-arrow [↑] represents the ASCII Ctrl-X character, numeric value 24.) [...]

    — Template:Comma separated entries

    Script error: No such module "Check for unknown parameters".
  10. ↑ Script error: No such module "citation/CS1". (NB. MSDOSTIP.TXT is part of MPDOSTIP.ZIP, maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the MSDOSTIP.TXT file.) [4]
  11. ↑ Script error: No such module "citation/CS1". (NB. The provided link points to a HTML-converted version of the 4DOS5TIP.TXT file, which is part of the MPDOSTIP.ZIP collection.) [5]
  12. ↑ Script error: No such module "citation/CS1". (xviii+856+vi pages, 3.5"-floppy) Errata: [6] [7]
  13. ↑ Script error: No such module "citation/CS1".
Cite error: <ref> tag with name "Microsoft_COMMAND" defined in <references> is not used in prior text.

Script error: No such module "Check for unknown parameters".

Further reading

<templatestyles src="Template:Quote_box/styles.css" />

[...] all MS-DOS versions prior to Windows 95 [...] used a COM style COMMAND.COM file which has a special signature at the start of the file [...] queried by the MS-DOS BIOS before it loads the shell, but not by the DR-DOS BIOS [...] COMMAND.COM would [...] check that it is running on the "correct" DOS version, so if you would load their COMMAND.COM under DR-DOS, you would receive a "Bad version" error message and their COMMAND.COM would exit, so DR-DOS would [...] display an error message "Bad or missing command interpreter" (if DR-DOS was trying to load the SHELL= command processor after having finished CONFIG.SYS processing). In this case, you could enter the path to a valid DR-DOS COMMAND.COM (C:\DRDOS\COMMAND.COM) and everything was fine. Now, things have changed since MS-DOS 7.0 [...] COMMAND.COM has internally become an EXE style file, so there is no magic [...] signature [...] to check [...] thus no way for DR-DOS to rule out an incompatible COMMAND.COM. Further, their COMMAND.COM no longer does any version checks, but [...] does not work under DR-DOS [...] just crashes [...] the PC DOS COMMAND.COM works fine under DR-DOS [...]

Script error: No such module "citation/CS1".

Script error: No such module "Check for unknown parameters".

External links

  • Template:Github - Source code to COMMAND.COM version A067 released by Microsoft as part of MS-DOS 4.0
  • Template:GitHub – Source code to COMMAND.COM version 2.11 released by Microsoft as part of MS-DOS 2.0
  • Template:GitHub – Source code to COMMAND.COM version 1.17 released by Microsoft as part of MS-DOS 1.25
  • FreeCom – COMMAND.COM implementation of FreeDOS

Script error: No such module "Navbox". Script error: No such module "Navbox". Template:DOS system files

Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=COMMAND.COM&oldid=4363198"