Hi
i have a problem executing a php script from a form and I'm clueless where I'm wrong.

These are the files used:
/etc/inc/rrd/rc	is a php script that execute /usr/local/bin/update_rrd.php which
is running endlessly in background with
exec("/usr/local/bin/update_rrd.php > /dev/null 2>&1 & echo \$! > /var/run/update_rrd_main.pid")
and when executed at boottime everything works fine, executing a ps -auxw i get

root     133  0.0  7.3  4020 3304 con- S     5:41PM   0:00.71 /usr/local/bin/php -f 
/usr/local/bin/update_rrd.php


The problem is that I want to stop and restart the update process but after killing it
when i try to re-execute it with the same exec() as above but from a web page the php script doesn't

start , i get the PID in /var/run but the executing ps there is no trace of update_rrd.php


thanks in advance for any help