.c and ideas...

// output-example-basic: sysfs-gpio.c:146: gpio_is_output: Assertion `c == 'i' || c == 'o'' failed.
// Aborted

// Error from the lib!

// Source below:

#include "sysfs-gpio.h"
#include <stdio.h>

int main()
{
        struct Gpio gpio = GPIO_INITIALIZER;
        gpio_open_output( &gpio, "/sys/class/leds/relay-jp3", 0 );

        int const timeout_ms = 3000;  // -1 = no timeout
        gpio_open( &gpio, "/sys/class/leds/relay-jp3", 0 );
        if( gpio_is_output( &gpio ) ) {
                gpio_write( &gpio, 0 );
        } else {
                gpio_set_direction_output( &gpio, 1 );
        }

        printf( "Print in %d milliseconds.\n ", timeout_ms );

        gpio_close( &gpio );
        return 0;
}

// I changed some of the source to handle the GPIOs on the am335x to Relays for the RelayCape.

Seth