AUTOEXEC.BAT
is a system file that was originally on
DOS
DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems.
DOS may also refer to:
Computing
* Data over signalling (DoS), multiplexing data onto a signalling channel
* Denial-of-service attack (DoS), an attack on a communicat ...
-type operating systems. It is a plain-text
batch file in the
root directory
In a computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the trunk of a tree, as the starting point where all branche ...
of the
boot device. The name of the file is an abbreviation of "automatic execution", which describes its function in automatically executing
commands on system startup; the filename was coined in response to the
8.3 filename
An 8.3 filename (also called a short filename or SFN) is a filename convention used by old versions of DOS and versions of Microsoft Windows prior to Windows 95 and Windows NT 3.5. It is also used in modern Microsoft operating systems as an altern ...
limitations of the
FAT file system family.
Usage
AUTOEXEC.BAT
is read upon startup by all versions of DOS, including MS-DOS version 7.x as used in
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 ...
and
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 ...
.
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 ...
only parses environment variables as part of its attempts to reduce legacy dependencies,
but this can be worked around.
The filename was also used by (DCP), an MS-DOS derivative by the former East-German
VEB Robotron.
In Korean versions of MS-DOS/PC DOS 4.01 and higher (except for PC DOS 7 and 2000), if the current country code is set to 82 (for Korea) and no
/P:filename
is given and no default
AUTOEXEC.BAT
is found,
COMMAND.COM
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 proc ...
will look for a file named
KAUTOEXE.BAT
instead in order to ensure that the
DBCS
A double-byte character set (DBCS) is a character encoding in which either all characters (including control characters) are encoded in two bytes, or merely every graphic character not representable by an accompanying single-byte character set ...
frontend drivers will be loaded even without properly set up
CONFIG.SYS
and
AUTOEXEC.BAT
files.
Under DOS, the file is executed by the primary copy of the command-line processor (typically
COMMAND.COM
) once the operating system has booted and the
CONFIG.SYS
file processing has finished. While DOS by itself provides no means to pass
batch file parameters to
COMMAND.COM
for
AUTOEXEC.BAT
processing, the alternative command-line processor
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
4DOS.INI
''
AutoExecParams
'' directive and
//AutoExecParams=
startup option to define such parameters.
Under
Concurrent 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 ...
,
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 ...
and
REAL/32, three initial parameters will be passed to either the corresponding
STARTxxy.BAT
(if it exists) or the generic
AUTOEXEC.BAT
startup file,
%1
holds the virtual console number,
%2
the 2-digit terminal number (xx) (with 00 being the main console) and
%3
the 1-digit session number (y).
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 ...
and its descendants
Windows XP
Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...
and
Windows Vista
Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
parse
AUTOEXEC.BAT
when a user logs on. As with Windows ME, anything other than setting environment variables is ignored.
Unlike
CONFIG.SYS
, the commands in
AUTOEXEC.BAT
can be entered at the interactive
command line interpreter. They are just standard commands that the computer operator wants to be executed automatically whenever the computer is started, and can include other batch files.
AUTOEXEC.BAT
is most often used to set
environment variables such as keyboard, soundcard, printer, and temporary file locations. It is also used to initiate low level system utilities, such as the following:
*
Virus scanner
Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware.
Antivirus software was originally developed to detect and remove computer viruses, hence the nam ...
s
* Disk caching software
* Mouse drivers
* Keyboard drivers
* CD drivers
* Miscellaneous other drivers
Example
In early versions of DOS,
AUTOEXEC.BAT
was by default very simple. The
DATE
and
TIME
Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, through the present, into the future. It is a component quantity of various me ...
commands were necessary as early
PC and
XT class machines did not have a battery backed-up
real-time clock
A real-time clock (RTC) is an electronic device (most often in the form of an integrated circuit) that measures the passage of time.
Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are pr ...
as default.
@ECHO OFF
CLS
DATE
TIME
VER
In non-US environments, the keyboard driver (like
KEYB FR
for the French keyboard) was also included. Later versions were often much expanded with numerous third-party device drivers. The following is a basic DOS 5 type
AUTOEXEC.BAT
configuration, consisting only of essential commands:
@ECHO OFF
PROMPT $P$G
PATH C:\DOS;C:\WINDOWS
SET TEMP=C:\TEMP
SET BLASTER=A220 I7 D1 T2
LH SMARTDRV.EXE
LH DOSKEY
LH MOUSE.COM /Y
This configuration sets common environment variables, loads a disk cache, places common directories into the default
PATH, and initializes the DOS mouse / keyboard drivers. The
PROMPT
command sets the
prompt to "C:\>" (when the
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 ...
is the root of the C drive) instead of simply "C>" (the default prompt, indicating only the working drive and not the directory therein).
In general, device drivers were loaded in
CONFIG.SYS
, and programs were loaded in the
AUTOEXEC.BAT
file. Some devices, such as mice, could be loaded either as a device driver in
CONFIG.SYS
, or as a
TSR in
AUTOEXEC.BAT
, depending upon the manufacturer.
In
MS-DOS 6.0 and higher, a DOS boot menu is configurable. This can be of great help to users who wish to have optimized boot configurations for various programs, such as DOS games and Windows.
@ECHO OFF
PROMPT $P$G
PATH C:\DOS;C:\WINDOWS
SET TEMP=C:\TEMP
SET BLASTER=A220 I7 D1 T2
GOTO %CONFIG%
:WIN
LH SMARTDRV.EXE
LH MOUSE.COM /Y
WIN
GOTO END
:XMS
LH SMARTDRV.EXE
LH DOSKEY
GOTO END
:END
The
GOTO %CONFIG%
line informs DOS to look up menu entries that were defined within
CONFIG.SYS
. Then, these profiles are named here and configured with the desired specific drivers and utilities. At the desired end of each specific configuration, a
GOTO
command redirects DOS to the
:END
section. Lines after
:END
will be used by all profiles.
Dual-booting DOS and Windows 9x
When installing
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 ...
over a preexisting DOS/Windows install,
CONFIG.SYS
and
AUTOEXEC.BAT
are renamed to
CONFIG.DOS
and
AUTOEXEC.DOS
. This is intended to ease dual booting between Windows 9x and DOS. When booting into DOS, they are temporarily renamed
CONFIG.SYS
and
AUTOEXEC.BAT
. Backups of the Windows 9x versions are made as
.W40
files.
Windows 9x also installs
MSDOS.SYS
MSDOS.SYS is a system file in MS-DOS and Windows 9x operating systems.
In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS kernel and is responsible for file access and program management. MSDOS.SYS is loaded by the DOS BI ...
, a configuration file, which will not boot Windows 95/98 if parameter
BOOTGUI=0
is loaded, and instead a DOS prompt will appear on the screen (Windows can still be loaded by calling the
WIN
command (file WIN.COM). This file contains some switches that designate how the system will boot, one of which controls whether or not the system automatically goes into Windows. This "BootGUI" option must be set to "0" in order to boot to a DOS prompt. By doing this, the system's operation essentially becomes that of a DOS/Windows pairing like with earlier Windows versions. Windows can be started as desired by typing
WIN
at the DOS prompt.
When installing
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
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- ...
7.02 and higher, the Windows version retains the name
AUTOEXEC.BAT
, while the file used by the DR-DOS
COMMAND.COM
is named
AUTODOS7.BAT
, referred to by the startup parameter
/P:filename.ext
in the
SHELL directive. It also differentiates the
CONFIG.SYS
file by using the name
DCONFIG.SYS
.
OS/2
The equivalent to
AUTOEXEC.BAT
under
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 ...
is the OS/2
STARTUP.CMD
file, however, genuine DOS sessions booted under OS/2 continue to use
AUTOEXEC.BAT
.
Windows NT
On
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 ...
and its derivatives,
Windows 2000
Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was offici ...
,
Windows Server 2003
Windows Server 2003 is the sixth version of Windows Server operating system produced by Microsoft. It is part of the Windows NT family of operating systems and was released to manufacturing on March 28, 2003 and generally available on April 24, 2 ...
and
Windows XP
Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...
, the equivalent file is called
AUTOEXEC.NT
and is located in the
%SystemRoot%\system32
directory. The file is not used during the operating system boot process; it is executed when the MS-DOS environment is started, which occurs when a DOS application is loaded.
The
AUTOEXEC.BAT
file may often be found on Windows NT in the root directory of the boot drive. Windows only considers the
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 ...
and
PATH
statements which it contains, in order to define
environment variables global to all users. Setting environment variables through this file may be interesting if for example MS-DOS is also booted from this drive (this requires that the drive be
FAT-formatted) or to keep the variables across a reinstall. This is an exotic usage today so the file usually remains empty. The
Tweak UI applet from the
Microsoft PowerToys collection allows to control this feature (''Parse AUTOEXEC.BAT at logon'').
See also
*
COMMAND.COM
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 proc ...
*
IBMBIO.COM
IBMBIO.COM is a system file in many DOS operating systems. It contains the system initialization code and all built-in device drivers. It also loads the DOS kernel ( IBMDOS.COM) and optional pre-loadable system components (like for disk compre ...
/
IO.SYS
is an essential part of MS-DOS and Windows 9x. It contains the default MS-DOS device drivers (hardware interfacing routines) and the DOS initialization program.
Boot sequence
In the PC bootup sequence, the first sector of the boot disk is ...
*
IBMDOS.COM
IBMDOS.COM is the filename of the DOS kernel. Loaded and initially invoked by the DOS BIOS in IBMBIO.COM during the boot process, it contains the hardware-independent parts of the operating system, including the embedded FAT12, FAT16 and ...
/
MSDOS.SYS
MSDOS.SYS is a system file in MS-DOS and Windows 9x operating systems.
In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS kernel and is responsible for file access and program management. MSDOS.SYS is loaded by the DOS BI ...
*
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 ...
*
CONFIG.SYS
*
AUTORUN.INF
References
{{DEFAULTSORT:Autoexec.Bat
DOS files
Configuration files
MSX-DOS