[comp.sys.ibm.pc] what SUBST does in a networked environment

tpf4434@DOMAIN_2.lerc.nasa.gov (03/11/90)

To: dmurdoch@watstat.waterloo.edu
Subject: Re: How can I set a PATH longer than 128 bytes ?
Newsgroups: comp.sys.ibm.pc
In-Reply-To: <1684@maytag.waterloo.edu>
References: <5762@ncrcae.Columbia.NCR.COM> <17140003@hplred.HP.COM> <1990Mar8.021622.13121@cec1.wustl.edu>
Organization: ops
Cc: 
Bcc: 

In article <1684@maytag.waterloo.edu> you write:
>In article <1990Mar8.021622.13121@cec1.wustl.edu> jcb2647@cec1.wustl.edu (James Christopher Beard) writes:
>>
>>If your path is of horrible length for some reason other than trying
>>to keep every known executable available at once, you can shorten the
>>number of characters in the path by giving some of the directories
>>"aliases" using the SUBST command a la 
>>
>>	SUBST E: C:\PROGRAMS\JOE\WORDPROC\WP
>>
>>Then you can include the virtual drive E: in your path.  Two notes,
>>though: 1) SUBST mustn't be used in a networked environment, which
>>seems like the place you're most likely to need it, and 2) for the
>>above to work, you need a command of the form "LASTDRIVE=E" in
>>CONFIG.SYS, where you replace "E" with the name of the
>>highest-lettered drive or virtual drive you will ever want to refer
>>to.
>
>Just out of interest:  what goes wrong in a networked environment?  I've
>been running for years (non-networked) with 
>  SUBST E: C:\
>in my autoexec; it makes it easy to maintain two views of the same disk,
>since I can CD independently on C: and E:.  What's going to go wrong
>if I ever hook up to a network?
>
>Duncan Murdoch





the problem stems from having the same disk drive addressible in two methods.
ie. as C: and as whatever you've SUBSTed for it..  the claim of trouble comes
from those who might try to use the same file from both devices at the same
time.. thus the dreaded record locking problem, or worse yet, updates to one
version, then having those updates wiped out by changes to the other..


if you're careful, nothing should happen.. but going strictly by the IBM
manuals, you're not supposed to use SUBST when making backups, or when 
connected to a network.. 

I've done both, and nothing major has gone wrong...


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*  Thanks,                                                    *
*      Ted Fabian            NASA Lewis Research Center       *
*                               Cleveland, Ohio               *
*                                                             *
*      phone:     216-433-6307  FTS 297-6307   |  disclaimer: *
*      email:     tpfabian@nasamail.nasa.gov   |  my opinions *
*                 tfabian@earth.lerc.nasa.gov  |  are my own  *
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