hi how to use multiple shields in Arduino?

if i have two..
example, GSM and Ethernet can this work simultaneously in void setup?

void setup(){

Serial.begin(9600);
    if (gsm.begin(2400)){
        Serial.println("\nstatus=READY");
        started=true;
    }
Ethernet.begin(mac, ip);
server.begin();

}

 

Are they using the same pins on the Arduino? You need to check what pins each shield uses on the underlying Arduino and then check if those pins support multiple devices (e.g. TWI, SPI).

If they are straight serial connections then I suspect they won't work reliably.