#include <wiringPi.h>
#include <stdlib.h>

int main(int argc,char *argv[])
{
    if(argc<2)
        return -1; 

    if(argc==2)
    {   
        wiringPiSetup();
        pinMode(0, OUTPUT);
        if(atoi(argv[1]) == 1)
            digitalWrite(0, HIGH);
        else if(atoi(argv[1]) == 0)
            digitalWrite(0, LOW);

        return 0;
    }   

    return 0;
}

$gpio readall

#include <bcm2835.h>
#include <stdio.h>

/*GPIO pin 17*/
#define PIN RPI_GPIO_P1_11

int main(int argc,char **argv)
{
    if(!bcm2835_init())
        return 1;
    
    bcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_OUTP);

    while(1)
    {   
        bcm2835_gpio_write(PIN,HIGH);

        bcm2835_delay(500);

        bcm2835_gpio_write(PIN,LOW);

        bcm2835_delay(500);
    }   
    bcm2835_close();
    return 0;
}