[Sheflug] fax script wizardry

[James Wallbank <xxxxx [at] xxxxxxxxxxx>]

Hi All,

I'm trying to find, write or rip off and modify a small shell script 
that's called by inittab that will convert incoming faxes into jpegs.

I can do the conversion no problem (ImageMagick rocks!) but I'm 
having trouble with the logic. This script's going to hang around in 
the background until a fax appears in /var/spool/fax/incoming/. Then, 
once the fax has arrived it's going to do the conversion and move it 
somewhere else. Then it'll exit and respawn ready for the next fax (I 
hope).

The trouble I'm having is with the test condition.

I can test for the existence of a file, but that's not enough: in the 
first moments that a fax arrives it's incomplete (just the first few 
bytes of the file) and then it grows bigger until it's fully there. 
And it isn't possible to predict how long it'll take to arrive, 
either. Only after its size stabilises should the script start to do 
its evil work.

(I could put in  a really long delay as a kludge to make sure the 
whole fax has arrived, but I'd like the script to respond as fast as 
possible so that there isn't a massive build-up of unprocessed faxes 
if incoming traffic is heavy. If that happens then the script will be 
waiting each time it detects a new file, and if there's a backlog 
it'll just get worse and worse!)

Any suggestions how to do this? I understand that Hylafax has the 
option to call a script after a fax arrives, but I'm using rungetty - 
which doesn't seem to have this option.

If you've made a script to do this sort of "wait until" function can you help?

Cheers,

James
=====
-- 
who: James Wallbank
org: Redundant Technology Initiative
tel: +44 114 2495522
fax: +44 114 2495533
eml: rti [at] lowtech.org
web: www.lowtech.org
loc: Access Space
      1 Sidney Street
      Sheffield
      S1 4RG
      UK
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