| Re: Passing arguments at runtime [message #31498 is a reply to message #31490] |
Tue, 23 July 2002 21:03  |
Chris Mulliss
Messages: 5
Registered: March 2000
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Junior Member |
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Try using environment variables to pass simple parameters into runtime
applications.
"Daniel Peduzzi" <peduzzi@attbi.com> wrote in message
news:aXV_8.127643$uw.72406@rwcrnsc51.ops.asp.att.net...
> My understanding is that the common (only?) method of passing parameters
> to an IDL program, restored at runtime using the IDL -rt option, is to
read them
> from a temporary file (e.g. "input.dat".) I've been using this technique
for years,
> and it works well for cases where there is no chance of the same "sav"
file being
> restored by multiple processes.
>
> However, dangers arise when multiple processes restore the same "sav"
> file, since the uniquely-named "input.dat" file is in danger of being read
> or changed by the wrong process.
>
> As an example: I have a c-shell script which is kicked off whenever a
data file
> appears in a directory. This can happen several times per hour. The
script
> takes the data file name, writes it to the temporary "input.dat" file, and
starts
> the IDL program which reads the data file name from "input.dat" and
immediately
> deletes "input.dat".
>
> To further protect against cases where the IDL program is restored by
parallel
> processes, I've tried to name the temporary file something unique, such as
> "input.$$" (where $$ denotes the process ID). Within the IDL program, I
get
> the most recently created input.* file via SPAWN, 'ls -1t input.*'. But
this can still
> fail when 2 or more processes are started at the same time.
>
> I was wondering how other folks have handled this situation, and if maybe
> there are other solutions which are not file-based and therefore prone to
> synchronization problems.
>
> Dan
>
> ---------------------------------------
> Daniel C. Peduzzi
> peduzzi@attbi.com
> ---------------------------------------
>
>
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