[OpenVPN Client] How to Use OpenVPN Client in any linux distro

# openvpn --config /var/tmp/happy.ovpn --tmp-dir /var/tmp

Fri Sep  4 17:05:39 2000 OpenVPN 2.3.7 armeb-unknown-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [MH] [IPv6] built on Sep  4 2000
Fri Sep  4 17:05:39 2000 library versions: OpenSSL 1.0.1 14 Mar 2012, LZO 2.08
Enter Auth Username:
Enter Auth Password:
Fri Sep  4 17:05:49 2000 UDPv4 link local: [undef]
Fri Sep  4 17:05:49 2000 UDPv4 link remote: [AF_INET]222.6.3.52:1194
Fri Sep  4 17:05:49 2000 WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this
Fri Sep  4 17:05:51 2000 [happy] Peer Connection Initiated with [AF_INET]222.6.3.52:1194
Fri Sep  4 17:05:53 2000 TUN/TAP device tun0 opened
Fri Sep  4 17:05:53 2000 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Fri Sep  4 17:05:53 2000 /sbin/ifconfig tun0 10.8.0.10 pointopoint 10.8.0.9 mtu 1500
Fri Sep  4 17:05:53 2000 Initialization Sequence Completed

Reference:

• [Linux] 架設 OpenVPN server 與 OpenVPN client 設定 @ Ubuntu 12.04