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CONFIG.SYS
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STARTUP.CMD
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MSDOS.SYS
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AUTOEXEC.BAT
EXPLANATION
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 function in automatically executing commands on system startup; the filename was coined in response to the 8.3 filename limitations of the FAT file system family.
AUTOEXEC.BAT
is read upon startup by all versions of DOS, including MS-DOS version 7.x as used in
Windows 95 and
Windows 98.
Windows ME only parses environment variables as part of its attempts to reduce legacy dependencies,
[1] but this can be worked around.
[2]
The filename was also used by
Disk Control Program [de] (DCP), an MS-DOS derivative by the former East-German
VEB Robotron.
[3]
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
will look for a file named
KAUTOEXE.BAT
instead in order to ensure that the
DBCS frontend drivers will be loaded even without properly set up
CONFIG.SYS
and
AUTOEXEC.BAT
files.
[4]
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 supports a
4DOS.INI
AutoExecParams
directive and
//AutoExecParams=
startup option to define such parameters.
[5] Under
Concurrent DOS,
Multiuser DOS 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,
[6] %2
the 2-digit terminal number (xx) (with 00 being the main console) and
%3
the 1-digit session number (y).
[7]
Windows NT and its descendants
Windows XP and
Windows Vista parse
AUTOEXEC.BAT
when a user logs on. As with Windows ME, anything other than setting environment variables is ignored.
[8] 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 scanners
- Disk caching software
- Mouse drivers
- Keyboard drivers
- CD drivers
- Miscellaneous other drivers