Hooks being run twice (same class)

[Steffen Grunewald]

Good morning,

I've run into something that could be bug or feature, and would like to hear
your opinion.

We know that FAI's class scripts output a series of class names.
By mapping entries of "lshw" output to, e.g., ethernet chip types, one may
get multiple instances of the same class (nowadays many ethernet cards come
with multiple ports).

FAI notices this, and warns.  So far so good.
Or not.

I haven't yet found a means to shrink the classes list to avoid duplicates.
(They don't need to follow each other directly as there may be multiple
classes matching one hardware feature, and sorting is forbidden.)

Now, with a rather (still) special case, I noticed that a hook *.CLASS would
be run twice if CLASS had been added to the list twice.
Not really surprising, one should think... To me, it was.

Is there an established way to avoid the second run?
(I could imagine a mechanism similar to C headers: set a semaphor file once
a hook has been executed, and test for that at the beginning of each run...
This certainly could be automated? and perhaps already has?)

Thanks,
 Steffen


-- 
Steffen Grunewald, Cluster Administrator
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
Am Mühlenberg 1 * D-14476 Potsdam-Golm * Germany
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Mail: steffen.grunewald(at)aei.mpg.de
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