# Network Connections List
networksetup -listallhardwareports

# Enable or Disable Device (en0 is wi-fi by default on os x)
networksetup -setairportpower en0 on
networksetup -setairportpower en0 off 

# Join Wi-Fi Network 
networksetup -setairportnetwork en0 SSID_OF_WIRELESS_NETWORK WIRELESS_NETWORK_PASSPHRASE

# Delete a Wi-Fi network profile
networksetup -removepreferredwirelessnetwork en0 SSID_OF_NETWORK

# Remove all stored Wi-Fi network profiles
networksetup -removeallpreferredwirelessnetworks en0

# Create a Wi-Fi network profile
# INDEX_NUMBER - Numerical value to assigns a position in the list of preferred
# wireless networks. A value of "0" adds to the network to the top of the list.
networksetup -addpreferredwirelessnetworkatindex en0 SSID_OF_NETWORK INDEX_NUMBER SECURITY_OF_WIRELESS_NETWORK WIRELESS_NETWORK_PASSPHRASE