/usr/share/arduino/ is in arduino-mighty-1284p 0~svn20130430-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/arduino/hardware/
/usr/share/arduino/hardware/mighty-1284p/
/usr/share/arduino/hardware/mighty-1284p/boards.txt
/usr/share/arduino/hardware/mighty-1284p/bootloaders/
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/Makefile
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/boot.h
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/optiboot.c
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/optiboot_atmega1284p.hex
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/optiboot_atmega1284p.lst
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/pin_defs.h
/usr/share/arduino/hardware/mighty-1284p/bootloaders/optiboot/stk500.h
/usr/share/arduino/hardware/mighty-1284p/bootloaders/standard/
/usr/share/arduino/hardware/mighty-1284p/bootloaders/standard/ATmegaBOOT.c
/usr/share/arduino/hardware/mighty-1284p/bootloaders/standard/ATmegaBOOT_1284P.hex
/usr/share/arduino/hardware/mighty-1284p/bootloaders/standard/ATmegaBOOT_1284P_8MHz.hex
/usr/share/arduino/hardware/mighty-1284p/bootloaders/standard/Makefile
/usr/share/arduino/hardware/mighty-1284p/cores/
/usr/share/arduino/hardware/mighty-1284p/cores/standard/
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Arduino.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/CDC.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Client.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/HID.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/HardwareSerial.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/HardwareSerial.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/IPAddress.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/IPAddress.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Platform.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Print.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Print.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Printable.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Server.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Stream.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Stream.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Tone.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/USBAPI.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/USBCore.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/USBCore.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/USBDesc.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/Udp.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/WCharacter.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/WInterrupts.c
/usr/share/arduino/hardware/mighty-1284p/cores/standard/WMath.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/WString.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/WString.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/binary.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/main.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/new.cpp
/usr/share/arduino/hardware/mighty-1284p/cores/standard/new.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring.c
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring_analog.c
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring_digital.c
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring_private.h
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring_pulse.c
/usr/share/arduino/hardware/mighty-1284p/cores/standard/wiring_shift.c
/usr/share/arduino/hardware/mighty-1284p/variants/
/usr/share/arduino/hardware/mighty-1284p/variants/avr_developers/
/usr/share/arduino/hardware/mighty-1284p/variants/avr_developers/README
/usr/share/arduino/hardware/mighty-1284p/variants/avr_developers/pins_arduino.h
/usr/share/arduino/hardware/mighty-1284p/variants/bobuino/
/usr/share/arduino/hardware/mighty-1284p/variants/bobuino/pins.ods
/usr/share/arduino/hardware/mighty-1284p/variants/bobuino/pins_arduino.h
/usr/share/arduino/hardware/mighty-1284p/variants/standard/
/usr/share/arduino/hardware/mighty-1284p/variants/standard/pins_arduino.h