Shell Programming and Scripting

#!/bin/bash

MODEM="/dev/ttyUSB3"
TMP="./response"

get_response ()
{
        local ECHO
        # cat will read the response, then die on timeout
        cat <&5 >$TMP &
        echo "$1" >&5
        # wait for cat to die
        wait $!

        exec 6<$TMP
        read ECHO <&6
        if [ "$ECHO" != "$1" ]
        then
                exec 6<&-
                return 1
        fi

        read ECHO <&6
        read RESPONSE <&6
        exec 6<&-
        return 0
}



# Clear out old response
: > $TMP

# Set modem with timeout of 5/10 a second
stty -F "$MODEM" 9600 -echo igncr -icanon onlcr ixon min 0 time 5

# Open modem on FD 5
exec 5<>"$MODEM"

get_response "AT+CGMI" || echo "Bad response"
echo "Response was '${RESPONSE}'"       ;       cat $TMP

echo

get_response "AT" || echo "Bad response"
echo "Response was '${RESPONSE}'"       ;       cat $TMP

exec 5<&-

sh scriptmodem.sh

chmod u+x scriptmodem.sh
./scriptmodem.sh

send AT+CREG?
IF not exist /dev/ttyUSB3 echo "MODEM NOT CONNECTED" and exit
ELSE (exist /dev/ttyUSB3) {
send AT+CREG?
if ouput is different from +creg: 0,1 then echo "MODEM NOT REGISTRED ERROR 1" and redo at+creg if is still different from +creg: 0,1 then echo "Modem  not registred ERROR 2"
AT!PADCONN=1
if output is different from CONNECTED 1,0 then "IMPOSSIBLE OPEN A SOCKET  ERROR 1" and redo at!PADCONN=1
and if is still different from CONNECTED 1,0 then echo "IMPOSSIBLE OPEN A SOCKET ERROR 2"
}

send AT+CREG?
if ouput is different from +creg: 0,1 then echo "MODEM NOT REGISTRED ERROR 1" and redo at+creg if is still different from +creg: 0,1 then echo "Modem  not registred ERROR 2"