[plug] Perl 'tie' equivalent for Linux files (not a Perl question)

[John Usher (Maptek)]

I know this is an very late reply, but have you had a look at
lufs.sourceforge.net?

...John...

-----Original Message-----
From: ryan at is.as.geeky.as [mailto:ryan at is.as.geeky.as] 
Sent: Friday, 4 October 2002 3:39 PM
To: plug at plug.linux.org.au
Subject: [plug] Perl 'tie' equivalent for Linux files (not a Perl
question)


Those of you familiar with the tie command in Perl might understand what
I
want to do.  It is the only thing I can think of to compare it to ...
well
that and database triggers.

I want to 'tie' a script to a system file so that whenever that file is
accessed the script is run and dumps its output into that file giving
the
impression the file is by all other means static.

=================================================
Example - we'll call this magical file 'thefile':

thefile could be linked to a script - lets make it easy and use
/bin/date as
the script

So I'd expect to see

$ cat thefile
Fri Oct  4 15:17:45 WST 2002

and in some mystery place there is some sort of magical 'thefile ->(<-)
/bin/date' link.
=================================================

Sure I could just symlink it to the script and run ./thefile but i need
thefile to present itself to all applications as a static text file.

The actual use of this is I want to be able to refer to a system file as
an
ordinary file but actually have it contain a current database schema
dump
that would be updated (via the script) every time the file was accessed.
I
can see that defining 'accessed' could be a hard thing ... and I can
also
see all of you frowning and wondering what the hell I'm trying to do it
like
that for :)

An alternative to look at it another way would be to set up a cron
script
running every second to dump the schema to the file - that would
essentially
achieve a similar result.  The theory of it seems similar to triggers in
databases too if that helps anyone.  Perhaps by using a 'special'
filesystem
ala /proc this can be done?

Is there any such way or workaround to achieve this kind of thing?  If
not,
then my question is also still answered.

Thanks for reading  :)

Ryan