find /etc -maxdepth 2 -type f
/etc/LININO_CONTRIBUTORS.TXT
/etc/arduino/Caterina-Yun.hex
/etc/arduino/gpg_gen_key_batch
/etc/arduino/openwrt-yun-release
/etc/arduino/wifi_error_reasons.csv.gz
/etc/arduino/wifi_error_statuses.csv.gz
/etc/arduino/wifi_timezones.csv.gz
/etc/arduino/arduino_gpg.asc
/etc/arduino/arduino_gpg.pub
/etc/arduino/arduino_gpg.sec
/etc/avahi/avahi-daemon.conf
/etc/avahi/avahi-dnsconfd.action
/etc/avrdude.conf
/etc/banner
...

ATmega32u4 Code:

#include <Process.h>
void setup() {
  Bridge.begin();   // Initialize the Bridge
  Serial.begin(9600);   // Initialize the Serial
  while (!Serial);  // Wait until a Serial Monitor is connected.
  countfiles();
}
void loop() { }
void countfiles() {
  Process p;
  p.runShellCommand("find /etc -maxdepth 2 -type f");
  while (p.running());
  while (p.available()) {
    char c = p.read();
    Serial.print(c);
  }
}