File content as of revision 0:0282e73ca55b:

#include "mbed.h"
#include "USBHostMSD.h"
DigitalOut led(LED1);
void msd_task(void const *) {
    printf("init msd\n");
    USBHostMSD msd("usb");
    int i = 0;
    printf("wait for usb memory stick insertion\n");
    while(1) {

        // try to connect a MSD device
        while(!msd.connect()) {
            Thread::wait(500);
        }

        // in a loop, append a file
        // if the device is disconnected, we try to connect it again

        // append a file
        FILE * fp = fopen("/usb/test1.txt", "a");

        if (fp != NULL) {
            fprintf(fp, "Hello fun SD Card World: %d!\r\n", i++);
            printf("Goodbye World!\r\n");
            fclose(fp);
        } else {
            printf("FILE == NULL\r\n");
        }
        Thread::wait(500);
        printf("again\n");
        // if device disconnected, try to connect again
        while (msd.connected()) {
            Thread::wait(500);
        }
    }
}

int main() {
    Thread msdTask(msd_task, NULL, osPriorityNormal, 1024 * 4);
    while(1) {
        led=!led;
        Thread::wait(500);
    }
}