Shell Programming and Scripting

#!/bin/bash
# revision 2
modem=/dev/ttyUSB3
apn='web.omnitel.it'
m2m_host=82.91.28.127
m2m_port=9940
file=/home/giuseppe/Desktop/SCRIPTMODEM/imsi.txt

# print error to stderr and exit unsuccessfully
die() {
	echo "$@" >&2
	exit 1
}

# chat helper. try everything twice.
send_expect() {
	chat ABORT ERROR '' "$@" '\c' ||
	chat ABORT ERROR '' "$@" '\c' ||
	echo "Exit code: $?" >&2
}

# keep modem open, so CD doesn't go low and drop connection
# move terminal to FD3 to avoid redirects on everything else ...
exec 3<&1 >"$modem" <"$modem"

# setup modem options ...
stty -clocal cs8 -parenb -cstopb

[ -e "$modem" ] || die 'Modem not connected'
send_expect 'AT+CREG?' '+CREG: 0,1' ||
	die 'Modem not registered'
send_expect "AT!PADSETUP=1,2,${m2m_host},0,${m2m_port},0,1" 'OK' ||
	die 'M2M connection failed'
send_expect 'AT+CGDCONT=1,"IP","'"$apn"'"' 'OK' ||
	die 'APN setup failed'
send_expect 'AT!PADCONN=1' 'CONNECT' ||
	die 'Unable to open socket'

cat "$file"

# give user idea of success
echo "done" >&3