[Buildroot] Strange behavior with shell redirection

[Cyril HAENEL]

Hello all, sorry I don't know if I am in the good place to ask my 
question...
On an custom board based on the AT91SAM9260 processor, 
buildroot-2009.05, and jffs2 as root file system, I have an "autostart" 
script launched at board startup.
In this script (I use the true bash and not the busybox shell) I launch 
my application, and I redirect the output to a log file :

#!/bin/bash
cd /home/potentiostat
[...]
echo "Launching application"
./potentiostatApplication >> /var/log/potentiostat
# Reboot if application error
if [ $? -ne 0 ]
then
reboot
fi

I use ">>" for the redirection, thus normally each time this script is 
launched it should concatenate the new log after the older one.
But it's not the case, each time I startup the board I have a new log !!

I really don't understand this beahavior, any idea ?

Best Regards,
Cyril HAENEL

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Cyril Haenel
Registered Linux User #332632