ubuntu nexus 7

boern@boern-desktop:~$ sudo fastboot erase boot
[sudo] password for boern:
erasing 'boot'...
OKAY [  0.032s]
finished. total time: 0.032s
boern@boern-desktop:~$ sudo fastboot erase userdata
erasing 'userdata'...
OKAY [  4.929s]
finished. total time: 4.929s
boern@boern-desktop:~$ sudo fastboot flash boot /home/boern/Downloads/raring-preinstalled-desktop-armhf+nexus7.bootimg
sending 'boot' (8192 KB)...
OKAY [ 11.090s]
writing 'boot'...
OKAY [  0.327s]
finished. total time: 11.417s
boern@boern-desktop:~$ sudo fastboot flash userdata /home/boern/Downloads/raring-preinstalled-desktop-armhf+nexus7.raw
sending 'userdata' (677761 KB)...