Recover wireless of Ubuntu on MacBook Air 4,2

1. sudo apt-get --reinstall install bcmwl-kernel-source
2. sudo modprobe -r b43 ssb wl brcmfmac brcmsmac bcma
3. sudo modprobe wl

Broadcom 802.11 Linux STA wireless driver source

Recover accidentally deleted file as long as some process still has it open, on Linux

1. lsof | grep myfile
1. the second column is the process id
2. the number in the fourth column is the file descriptor
2. cp /proc/<process id>/fd/<file descriptor> myfile.saved

Taken: http://archive09.linux.com/articles/58142