Linux, UNIX

source  is a synonym for dot/period ' . ' in bash, but not in POSIX sh, so for maximum compatibility use the period. When a script is run using  source  it runs within the existing shell, any variables created or modified by the script will remain available after the script completes. In contrast if the script is run just as  filename , then a separate subshell (with a completely separate set of variables) would be spawned to run the script. ubu1404@ubuntu1404lb01:~$ bash script  Thu Mar 8 08:02:09 PST 2018 ubu1404@ubuntu1404lb01:~$ source script  bash: source: /usr/bin/script: cannot execute binary file ubu1404@ubuntu1404lb01:~$ script Script started, file is typescript ubu1404@ubuntu1404lb01:~$ mv script scr ubu1404@ubuntu1404lb01:~$ bash scr Thu Mar 8 08:02:47 PST 2018 ubu1404@ubuntu1404lb01:~$ source scr Thu Mar 8 08:02:51 PST 2018 ubu1404@ubuntu1404lb01:~$ ./scr Thu Mar 8 08:02:56 PST 2018 ubu1404@ubuntu1404lb01:~$ . ./scr Thu Mar 8 08:03:00 PST

https://www.digitalocean.com/community/tutorials/how-to-set-up-an-openvpn-server-on-ubuntu-14-04 V PN services are  implemented with a number  of different protocols, such as  Point-to-Point Tunneling Protocol  ( PPTP ),  Layer two tunneling protocol  ( L2TP ), IPSec, and SSL. In  this recipe, we will set up a free VPN server, OpenVPN. OpenVPN is an open source SSL VPN solution and provides a wide range of configurations. OpenVPN can be configured to use either TCP or UDP protocols. In this recipe, we will set up OpenVPN with its default UDP port 1194. / usr/share/easy-rsa ubuntu@ubuntu:/usr/share/easy-rsa$ ll total 128 drwxr-xr-x   2 root root  4096 Dec 25 12:45 ./ drwxr-xr-x 311 root root 12288 Dec 25 12:45 ../ -rwxr-xr-x   1 root root   119 Nov  8  2013 build-ca* -rwxr-xr-x   1 root root   352 Nov  8  2013 build-dh* -rwxr-xr-x   1 root root   188 Nov  8  2013 build-inter* -rwxr-xr-x   1 root root   163 Nov  8  2013 build-key* -rwxr-xr-x   1 root root   157 Nov  8  2