Apply VPN to a single process().
$ sudo bash ./vpnshift -c <OVPN FILE> -i <INTERFACE> -u <USER> [<COMMAND> [<ARG>...]]
Establish a VPN network namespace with a dummy command.
$ sudo bash ./vpnshift -c <OVPN FILE> -i <INTERFACE> -u <USER> ping google.com
..and attach multiple processes to it.
$ sudo ip netns exec <NAMESPACE> sudo -u <USER> [<COMMAND> [<ARG>...]]