I have arch installed on my hd, but I can't establish a WPA2-encrypted network connection because wpa_supplicant is not installed. On my arch live-usb there is wpa_supplicant and there I can establish the network connection.Is there any way to tell pacman of my live arch to install the wpa_supllicant package to my installed arch on /mnt ?
Arch Install wpa_supplicant from live arch to installed arch
linux;arch linux;pacman;wpa supplicant
Reading the pacman man page, it looks to me like you could do this:pacman --root /mnt -S wpa_supplicantwhile you have the live Arch CD booted, and the / partitioned mounted on /mnt.  That might be a little more complicated if you have a separate /usr partition.You'll probably have to fix up the /etc/wpa_supplicant/wpa_supplicant.conf file after you've rebooted from the HD, or fix it up in /mnt/ before the reboot.UPDATE 2017-04-02Either Arch or systemd has changed. Here's what you do now:Find wireless device name, use ip a or ifconfig -a  Mine is wlp12s0, USB wireless adaptors look  like wlp26f7u3Start wpa_supplicant: systemctl enable wpa_supplicant; systemctl start wpa_supplicant. This is the master process, or maybe I'm just superstitious.Make a wpa_supplicant.conf@wirelessdevicename file in /etc/wpa_supplicant. For my laptop, this is wpa_supplicant-wlp12s0.conf and I believe I just did cp wpa_supplicant.conf wpa_supplicant-wlp12s0.conf  There will exist a separate config file for each interface you start this way, and they can be configured differently.Start wpa_supplicant for that inteface.  For me, this looked like: systemctl enable wpa_supplicant@wlp12s0; systemctl start wpa_supplicant@wlp12s0  You device name will vary.It might help debug if you have journalctl -f running in a separate terminal. 