AUTOEXEC.BAT
batch file loaded automatically during MS-DOS and Windows 9x startup
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. In the autoexec.bat file one can execute every command being available either internally within the OS-specific command.com TSR or as an extra command (.com/.exe files)
Usage
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, but this can be worked around.
The filename was also used by Disk Control Program (DCP), an MS-DOS derivative by the former East-German VEB Robotron.
In Korean editions of MS-DOS/PC DOS version 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.
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. 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, %2 the 2-digit terminal number (xx) (with 00 being the main console) and %3 the 1-digit session number (y).
This brief starts where responsible research should: with the source description of “AUTOEXEC.BAT” as batch file loaded automatically during MS-DOS and Windows 9x startup. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as batch file loaded automatically during MS-DOS and Windows 9x startup. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 19, 2026. The linked authority identifier is Q300115. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2000.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “AUTOEXEC.BAT” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.