asterisk channels scripts

[Asterisk REQ]

Hi,
    I´m trying to monitor asterisk channels using exit value (between 0 and 255, I have no more concurrent calls) so, I try with this script:

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#!/bin/bash

chan=$(asterisk -rx "core show channels" |grep "active channels" |  awk '{ printf "%d",$(1) }')

echo $chan #for debug

exit $chan

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and monitrc:

#asterisk channels
check program asterisk-channelsv with path "/etc/monitscripts/asterisk_channels.sh"
    if status > 100 then alert

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but I can see the correct value on ECHO but monit always show 0, if I change "exit $chan" for "exit 2" monit shows 2 correctly.
Whats wrong? Any ideas?