How to connect to WiFi from the command line?

I think you want to keep using managed interface (by NetworkManager). nmcli is a command‐line tool for controlling NetworkManager.

• To see list of saved connections, use (<SavedWiFiConn>)

  nmcli c
  

• To see list of available WiFi hotspots (<WiFiSSID>)

  nmcli d wifi list
  

  or:

  sudo iwlist <WifiInterface> scanning
  

• To see list of interfaces (<WifiInterface>)

  ifconfig -a
  

Just change <WifiInterface>, <WiFiSSID>, <WiFiPassword> in the following commands to reflect your setup. If WiFi info already saved, easier way using <SavedWiFiConn> name of connection as it was saved in NetworkManager.

Ubuntu 16.04

##disconnect
nmcli d disconnect <WifiInterface>

##connect
nmcli d connect <WifiInterface>

Another way:

##disconnect
nmcli c down <SavedWiFiConn>

##connect
nmcli c up <SavedWiFiConn>

Ubuntu 15.10 & previous

##disconnect
nmcli d disconnect iface <WifiInterface>

##connect
nmcli d wifi connect <WiFiSSID> password <WiFiPassword> iface <WifiInterface>

Another way:

##disconnect:
nmcli c down id <SavedWiFiConn>

##connect:
nmcli c up id <SavedWiFiConn>

If your password isn't automatically recognized type this:

nmcli -a c up <SavedWiFiConn>

Reference: man nmcli

nmtui ncurses solution

Great interactive ncurses network manager option:

nmtui

If for some reason it is not installed, the Debian package is:

sudo apt install network-manager

Comes in the same package as nm-applet (the default top bar icon thing) and nm-cli, and is therefore widely available.

Screenshot:

Tested in Ubuntu 17.10.

If your wi-fi access point is saved, it will auto-connect. Turn wireless on or off with a simpler command:

nmcli nm wifi on
nmcli nm wifi off

on newer version:

nmcli radio wifi on
nmcli radio wifi off

For reference, see man nmcli.