How To: Restart Apple Mac OS X Airport Networking From the Bash Terminal

Procedure: How to restart Wifi (en0) using the terminal

1. Open the terminal.
2. Type the following command to shutdown en0 interface:
   sudo ifconfig en0 down
3. Type the following command to bring it back en0 interface:
   sudo ifconfig en0 up
4. Verify that interface is back online again:
   ifconfig -u en0

Sample session:

Fig.01: Enable and Disable OSX Wi-Fi

alias restart_en0='sudo ifconfig en0 down && sudo ifconfig en0 up'

To restart simply type:

restart_en0

Say hello to networksetup command

The networksetup is a configuration tool for network settings in OS X.

Use networksetup restart (on and off) Mac OS X networking

Type the following command to turn it off en0:
networksetup -setairportpower en0 off
OR
networksetup -setairportpower "Wi-Fi" off
Type the following command to turn it on en0:
networksetup -setairportpower en0 on
OR
networksetup -setairportpower "Wi-Fi" on
Sample outputs:

Wi-Fi is not a Wi-Fi interface.
Turning on the only airport interface found: en0

Both commands have many more options. See the man page by typing the following command:
man ifconfig
man networksetup