cy@ashtate.UUCP (Cy Shuster) (06/26/87)
In DOS 3.3, if you have FOO.BAT and FOO.COM in the same subdirectory, the COM program is always executed, even if you type "FOO.BAT" at the DOS prompt -- or even "CALL FOO.BAT" (didn't try DETACH :-) ). EXEs also override .BAT. Happens on a PS/2 Mod 30 as well as AT 339. Surely this isn't a feature? --Cy-- ashtate!cy@seismo.CSS.GOV
ralf@b.gp.cs.cmu.edu (Ralf Brown) (06/29/87)
In article <302@ashtate.UUCP> cy@ashtate.UUCP (Cy Shuster) writes: >In DOS 3.3, if you have FOO.BAT and FOO.COM in the same subdirectory, >the COM program is always executed, even if you type "FOO.BAT" at the >DOS prompt -- or even "CALL FOO.BAT" (didn't try DETACH :-) ). EXEs >also override .BAT. Happens on a PS/2 Mod 30 as well as AT 339. Surely >this isn't a feature? > >--Cy-- ashtate!cy@seismo.CSS.GOV Yep, it's a feature. It's been in DOS since 1.0, and maybe even since QDOS :-) The precedence order is .COM, .EXE, and finally .BAT. You don't expect that DOS can read your mind when you type FOO and decide whether you want FOO.COM, FOO.EXE, or FOO.BAT? :-) (Although I would kind of expect it to use .BAT on a CALL statement). Presumably .COM overrides .EXE because .COM is the final product of a compilation ending with EXE2BIN, and should thus be used in preference to the intermediate .EXE. BTW: any extension you give is simply ignored, thus FOO.XXX will work too. -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= ARPA: RALF@B.GP.CS.CMU.EDU USnail: Ralf Brown AT&T: (412) 268-3053 (school) Computer Science Department Carnegie-Mellon University DISCLAIMER? Who ever said I claimed anything? Pittsburgh, PA 15213 "I do not fear computers. I fear the lack of them..." -- Isaac Asimov
brown@nicmad.UUCP (Mr. Video) (06/29/87)
In article <302@ashtate.UUCP> cy@ashtate.UUCP (Cy Shuster) writes:
<In DOS 3.3, if you have FOO.BAT and FOO.COM in the same subdirectory,
<the COM program is always executed, even if you type "FOO.BAT" at the
<DOS prompt -- or even "CALL FOO.BAT" (didn't try DETACH :-) ). EXEs
<also override .BAT. Happens on a PS/2 Mod 30 as well as AT 339. Surely
<this isn't a feature?
Yep, it is a feature. The program searcher, within DOS, searches for the
program name, ignoring the extension. Search order is EXE, COM and then BAT.
In general, the rule is never have programs with the same name having different
extensions, reside in the same directory.
--
harvard-\ ihnp4--\
Mr. Video seismo!uwvax.......!nicmad!brown
rutgers-/ decvax--/
terminus-/ward@chinet.UUCP (ward) (06/29/87)
To the best of my knowledge, PC-DOS has never looked at file extensions typed as command names. In your message you mentioned being surprised that DOS 3.3 has COM files override BAT and EXE, so FOO.COM and FOO.BAT in the same dir causes FOO.COM to run. "Right". DOS has always been that way - just tested it on DOS 2.0, 3.2, and Toshiba T1100+ 2.11 - all ignore any extension, as has always been my experience. I often see people typing "edlin.com filename" and things like that - and never understood why. Ideally DOS would work like this: if a bat file exists, run it; if the bat file refers to the same name, run the COM or EXE. This would allow overriding COM and EXE with BAT yet still running the underlying executable code. A good example would be FORMAT.BAT which could execute FORMAT.COM, but for now, you've got to rename format.com formatx.com or something. Did YOU have a version of DOS that "understands" file extensions when executing commands or batch files?
rgale@pnet01.CTS.COM (Ryan Gale) (06/30/87)
ward@chinet.UUCP writes > Ideally DOS would work like this: if a bat file exists, run it; if > the bat file refers to the same name, run the COM or EXE. This would > allow overriding COM and EXE with BAT yet still running the underlying > executable code. A good example would be FORMAT.BAT which could execute > FORMAT.COM, but for now, you've got to rename format.com formatx.com or > something. My solution was to put all of my BAT files in their own subdirectory and put that subdirectory first on the PATH. COM and EXE files can still be run (instead of a same-named BAT) by specifying the full path name, but this is rarely needed (else why would you have the BAT file in the first place?). --- Ryan Gale UUCP: {hplabs!hp-sdd, sdcsvax, nosc}!crash!pnet01!rgale ARPA: crash!pnet01!rgale@nosc.mil INET: rgale@pnet01.CTS.COM
tr@wind.UUCP (07/01/87)
In article <302@ashtate.UUCP> cy@ashtate.UUCP (Cy Shuster) writes:
$ In DOS 3.3, if you have FOO.BAT and FOO.COM in the same subdirectory,
$ the COM program is always executed, even if you type "FOO.BAT" at the
$ DOS prompt -- or even "CALL FOO.BAT" (didn't try DETACH :-) ). EXEs
$ also override .BAT. Happens on a PS/2 Mod 30 as well as AT 339. Surely
$ this isn't a feature?
$
$ --Cy-- ashtate!cy@seismo.CSS.GOV
Call it a feature or a bug, but it has been that way with all the
versions of DOS that I can remember using.
Tom Reingold
INTERNET: tr@bellcore.bellcore.com
UUCP: {seismo,ihnp4,ucbvax,decvax}!bellcore!tr
{ulysses,allegra,clyde,princeton}!bellcore!trcy@ashtate.UUCP (Cy Shuster) (07/06/87)
Thanks for the reminders: if files FOO.COM, FOO.EXE, and FOO.BAT all exist and the external command "FOO" is typed, the search precedence has always been .COM, .EXE, and then .BAT (the way I remember the COM/EXE distinction is that after running EXE2BIN on a .EXE to make a .COM, you have to delete the .EXE to execute the new .COM). I apologize for not checking this behavior under prior DOS releases before blaming 3.3. I suspected 3.3 because I was testing the behavior of the new "CALL" statement. Anytime syntax calls for "drive:\path1\path2...\filespec" I tend to include the extension as well. I guess I never realized that if you keyed in the extension, it was ignored. --Cy-- cy@ashtate.UUCP