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Conference noted::hackers_v1

Title:	-={ H A C K E R S }=-
Notice:	Write locked - see NOTED::HACKERS
Moderator:	DIEHRD::MORRIS

Created:	Thu Feb 20 1986
Last Modified:	Mon Aug 03 1992
Last Successful Update:	Fri Jun 06 1997
Number of topics:	680
Total number of notes:	5456

624.0. "SHOW DEVICE/FILE" by BMT::MISRAHI (at the tone, please leave your ...) Mon Dec 07 1987 19:11

I executed the command		$SHOW DEVICE/FILE      and saw a whole 
bunch of files listed. Makes sense to me so far.

What I can't understand is why certain processes running this
application are listed multiple times for the same file.

How can a single process have a single file open 3 times - at once ?
This is true for more than one process, too.
    
Is this an application quirk, or a DCL feature ?

    
    /Jeff

T.R	Title	User	Personal Name	Date	Lines
624.1	answer is ...	BMT::MISRAHI	at the tone, please leave your ...	`Tue Dec 08 1987 18:12`	8
	I was thinking in COBOL terms - one open at a time. "C", macro etc. will let you open the file multiple times -- hence what I saw when I did SHOW DEVICE/FILE Thanks anyway. by the way - anyone know what happened to node BULOVA:: - can't get to it anymore.
624.2	Where oh were has BULOVA gone, Oh where oh where...	MONSTR::DUTKO	Nestor Dutko, VMS/VAXclusters CSSE	`Tue Dec 08 1987 18:32`	7
624.3		CASEE::VANDENHEUVEL	Make my Day	`Wed Dec 09 1987 07:21`	20
	Re .1, In COBOL you can also open a file multiple times. You will need multiple FDs that point to the same file. In an other conference you posted a sample output. That showed a single process opening the same data file three times. No problem with that. (ALL-IN-1 does it all the time :-). What I can not explain though is the fact that it showed the same pid having an EXE open three times. If that EXE is actually the image that is running, then I would be worried. (ofcourse if you manage to activate the same image three time, then that would explain the that the datafile is opened three times :-). So, I urge you to concentrate on the EXE. Hein.
624.4		BMT::MISRAHI	at the tone, please leave your ...	`Wed Dec 09 1987 11:53`	2
	ta very much. /Jeff.
624.5	What about..	MDVAX3::COAR	My hero? Vax Headroom, of course!	`Thu Dec 17 1987 21:16`	7
	I wonder.. Would three calls to LIB$FIND_IMAGE_SYMBOL open the image three separate times? Especially if you asked for three different symbols? On the other hand, what about a V3-linked image that uses all sorts of RTLs? I wouldn't be surprized if that might do it, too, under certain circumstances.. #ken :-)}
624.6	FIS is rather clever...	DUCATI::LASTOVICA	ain't juggling till there's 3 up	`Thu Dec 17 1987 22:27`	10
	LIB$F_I_S does pretty much the same thing as a DCL run command. It calls $IMGACT and $IMGFIX. It also reads the symbol table part of the image to return to you the value of the symbols after relocation into your image. It is smart enough to scan the list of currently activated images and will not open the image file again. It gets activated the first time and then scaned for symbols at each invocation. It does do direct I/O to the image file to get things that are not contained in the image portion that is activated, and I believe that it does this each time. The sources to LIB$F_I_S are very enlightening in how things work on a VAX...