CentOS - configure wireless from command line

1. Make sure about wpa_supplicant package
# rpm -qa | grep wpa_supplicant
On my laptop, I found wpa_supplicant-2.0-17.el7_1.x86_64

2. Get wifi interface name
# nmcli d
On my laptop, it showed
DEVICE      TYPE      STATE           CONNECTION
enp7s0         ethernet   unavailable     --
lo                 loopback unmanaged      --
wlp5s0         wifi         unmanaged      --

3. Add configuration to /etc/wpa_supplicant/wpa_supplicant.conf
=====================================================
ctrl_interface=/var/run/wpa_supplicant

network={
ssid="Your SSID"
psk="Your password"
}
=====================================================

4. Configure dhcp client in /etc/sysconfig/network
NETWORKING=yes
GATEWAY=<Your gateway>

5. Start wpa_supplicant daemon with option -i wlp5s0

For me, I start wpa_supplicant daemon by using systemd. I have to modify ExecStart in /lib/systemd/system/wpa_supplicant.service as follows:

ExecStart=/usr/sbin/wpa_supplicant -i wlp5s0 -u -f /var/log/wpa_supplicant.log -c /etc/wpa_supplicant/wpa_supplicant.conf

And then,

# systemctl start wpa_supplicant

Check log

# tail -f /var/log/wpa_supplicant.log