SCOUG-Programming Mailing List Archives

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Date:	Mon, 25 Oct 1999 20:21:57 PDT
From:	"Aaron Lawrence" <aaronl@pec.co.nz >
Reply-To:	scoug-programming@scoug.com
To:	scoug-programming@scoug.com
Subject:	SCOUG-Programming: REXX file lock/unlock, program instances

Content Type: text/plain

> -- How do I lock a file, unlock it after using it, and what error code
> does another program receive if it attempts to open/lock an
> already-locked file?
In rexx, all files are opened non-share, so are automatically locked (AFAIK) and
no other program can access them

> -- How can an executing REXX .cmd file find out if it is already running?
Some sort of nasty external flag e.g. create a file at startup. Check if it
already exists. Delete at finish etc.
Unfortunately since Rexx is not really a "program" you can't use OS/2 semaphores
which are better, because with a real program they are automatically destroyed
if the program ends.

Basically Rexx is best not used for situations where multiprocessing matters (or
any "serious" task) IMHO

Aaron

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