HTTP monitoring in GTM

It turns out that in GTM, an HTTP monitor will immediately down a server upon a failure. There is no "you can fail 3 times in a row before I mark you down" in GTM. Thus, I have tried to write a shell script as an EAV for GTM that does the same thing:

 
 !/bin/sh 
  
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  @() $Id: http_monitor_cURL+GET,v 1.0 2007/06/28 16:10:15 deb Exp $ 
  (based on sample_monitor,v 1.3 2005/02/04 18:47:17 saxon) 
  
  these arguments supplied automatically for all external monitors: 
  $1 = IP (IPv6 notation. IPv4 addresses are passed in the form  
                          ::ffff:w.x.y.z 
                          where "w.x.y.z" is the IPv4 address) 
  $2 = port (decimal, host byte order) 
  
  Additional command line arguments ($3 and higher) may be specified in the monitor template 
  This example does not expect any additional command line arguments 
  
  Name/Value pairs may also be specified in the monitor template 
  This example expects the following Name/Vaule pairs: 
   URI  = the URI to request from the server 
   RECV = the expected response (not case sensitive) 
   TRY = the number of tries 
  
  remove IPv6/IPv4 compatibility prefix (LTM passes addresses in IPv6 format) 
 IP=`echo ${1} | sed 's/::ffff://'` 
 PORT=${2} 
  
 PIDFILE="/var/run/`basename ${0}`.${IP}_${PORT}.pid" 
  kill of the last instance of this monitor if hung and log current pid 
 if [ -f $PIDFILE ] 
 then 
    kill -9 `cat $PIDFILE` > /dev/null 2>&1 
 fi 
 echo "$$" > $PIDFILE 
  
 success=0 
 n=${TRY} 
  loop TRY times 
 for (( i = 1; i <= $n; i++ )) 
 do 
  send request & check for expected response 
    curl -fNsi http://${IP}:${PORT}${URI} | grep -i "${RECV}" 2>&1 > /dev/null 
  
  mark node UP if expected response was received 
    if [ $? -eq 0 ] 
    then 
        success=1 
    fi 
    sleep 3 
 done 
  
 if [ $success == 1 ] 
 then 
     echo "UP" 
 fi 
  
 rm -f $PIDFILE 
 exit 
 

It seems to work, but I don't quite feel sure about it. Can someone look this over for errors? Thanks.