Easily disable network connection of Mac

Diable:

sudo ifconfig en0 down

Enable:

sudo ifconfig en0 up

Add PATH for MAC or Linux temporarily

PATH=$PATH\:/dir/path

/dir/path is the path you want to add to your $PATH

Some tips for Mac users

Show all hidden files:

defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder

Unlock folder recursively:

sudo chflags -R nouchg * ./