Steps:
Step 1: Create EC2 Instance in AWS.
We need launch new instance with “Ubuntu Server 22.04 LTS Free tier eligible”

Step2: Connect EC2 Instance.
Connect to EC2 Instance with EC2 Instance Connect or SSH.

Step3: Install OpenVPN Server.
After successfully logging into the Ubuntu server, we can now start setting up OpenVPN. We will use the OpenVPN script available on Github (angristan script). We first need to update the default DNS of the Ubuntu instance. To update the DNS configuration, you must first switch the user account from “ubuntu” to “root” by running the following command:
sudo su
Once, you have the root user account, change default DNS to google DNS (8.8.8.8) in /run/systemd/resolve/stub-resolv.conf directory.
nano /run/systemd/resolve/stub-resolv.conf
Then set the nameserver to Google DNS
nameserver 8.8.8.8 options edns0 trust-ad search .
To save the changes, press the CTRL+X+Y then Enter.
Installation using the OpenVPN script is quite easy. It is recommended that when you install a Linux service or module is to make sure that the system is up-to-date. Execute below command to check for updates of the libraries and modules.
apt-get update apt-get upgrade curl -O https://raw.githubusercontent.com/angristan/openvpn-install/master/openvpn-install.sh chmod +x openvpn-install.sh
Then run it:
./openvpn-install.sh
You need to run the script as root and have the TUN module enabled.
Enter network interface IP address. By default, EC2 will give you a local IP address and the OpenVPN script will ask you for your Public IPv4 address or hostname. Copy the Public IP address of EC2 Instance, then press enter enter to proceed.
I need to know the IPv4 address of the network interface you want OpenVPN listening to. Unless your server is behind NAT, it should be your public IPv4 address. IP address: 1.1.1.1
It seems this server is behind NAT. What is its public IPv4 address or hostname? We need it for the clients to connect to the server. Public IPv4 address or hostname: 2.2.2.2
Then, disable the IPv6 support by entering “n” on the input field.
Enter default OpenVPN port by choosing 1.
What port do you want OpenVPN to listen to? 1) Default: 1194 2) Custom 3) Random [49152-65535] Port choice [1-3]: 1
It is recommended to use UDP protocol for faster connection. Choose number 1 option.
What protocol do you want OpenVPN to use? UDP is faster. Unless it is not available, you shouldn't use TCP. 1) UDP 2) TCP Protocol [1-2]: 1
For this tutorial, you will use your current system resolver. Choose number 1 option.
What DNS resolvers do you want to use with the VPN? 1) Current system resolvers (from /etc/resolv.conf) 2) Self-hosted DNS Resolver (Unbound) 3) Cloudflare (Anycast: worldwide) 4) Quad9 (Anycast: worldwide) 5) Quad9 uncensored (Anycast: worldwide) 6) FDN (France) 7) DNS.WATCH (Germany) 8) OpenDNS (Anycast: worldwide) 9) Google (Anycast: worldwide) 10) Yandex Basic (Russia) 11) AdGuard DNS (Anycast: worldwide) 12) NextDNS (Anycast: worldwide) 13) Custom DNS [1-12]: 1
Choose the default n option.
Do you want to use compression? It is not recommended since the VORACLE attack makes use of it. Enable compression? [y/n]: n
Do Do you want to customize encryption settings? Unless you know what you're doing, you should stick with the default parameters provided by the script. Note that whatever you choose, all the choices presented in the script are safe. (Unlike OpenVPN's defaults) See https://github.com/angristan/openvpn-install#security-and-encryption to learn more. Customize encryption settings? [y/n]: n
Finally, your OpenVPN settings are now ready.
Okay, that was all I needed. We are ready to setup your OpenVPN server now. You will be able to generate a client at the end of the installation. Press any key to continue...
OpenVPN will start installing the required configurations and services. At the end of installation, OpenVPN will ask to enter client name to generate a client certificate. Then choose a passwordless client for your client certificate.
Follow the instruction on how to download the client certificate.
Now that you have successfully install the OpenVPN, start the OpenVPN service by executing the below command.
openvpn /etc/openvpn/server.conf
Check for tun0 interface if exist.
ip a
There you have it. Your OpenVPN server is now ready.

Step4: Configure EC2 Instance Security group
In order for the OpenVPN client to connect to the OpenVPN server, you need to configure the EC2 Security Group of Ubuntu instance. OpenVPN commonly uses UDP 1194 as a default port to which you need to add in EC2 Security group inbound rules.
Go to the EC2 dashboard and navigate to the Network & Security menu. Choose the Security Groups option, then choose the Security group name that was configured before.
In the bottom EC2 panel, go to the Security group rules menu, then choose the Inbound rules option. Choose Edit inbound rules button to add new inbound rules.
Choose Add rule then fill out the required input fields.
Save the new added rule.
Congratulations! You have successfully setup an OpenVPN server in AWS EC2 on Ubuntu 22:04 LTS instance.

Prerequisites:
AWS Account
Ubuntu 22.04 LTS EC2 Instance

Link: https://cytoolz.com/blog/openvpn-server-on-ubuntu22-04-ec2-instance

На двух рабочих компьютерах появился интересный глюк: запускается AutoCAD 2010, появляется логотип, на доли секунды появляется главное окно AutoCAD и тут же закрывается. Никаких ошибок не выдает и системный журнал абсолютно чист. Переустановка автокада и удаление профайла пользователя не помогли. На всех остальные компьютерах программы Autodesk работают нормально.
Решение
1. Удалить или переименовать файл CascadeInfo.cas В Windows 7: C:\ProgramData\Autodesk\Adlm

2. Запустить AutoCAD. Автокад создал новый файл CascadeInfo.cas и запустился. Проблема решена.

1. Overview
In this quick tutorial, we’ll focus on how to add a path to the Linux PATH variable.

2. PATH Variable
The PATH variable is an environment variable that contains an ordered list of paths that Linux will search for executables when running a command. Using these paths means that we do not have to specify an absolute path when running a command.

For example, if we want to print Hello, world!, the command echo can be used rather than /bin/echo so long as /bin is in PATH:

echo “Hello, world!”
Linux traverses the colon-separated paths in order until finding an executable. Thus, Linux uses the first path if two paths contain the desired executable.

We can print the current value of the PATH variable by echoing the PATH environment variable:
echo $PATH
We should see a list of colon-separated paths (exact paths may differ):

/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

3. Adding a New Path
We add a new path to the PATH variable using the export command.

To prepend a new path, such as /some/new/path, we reassign the PATH variable with our new path at the beginning of the existing PATH variable (represented by $PATH):

export PATH=/some/new/path:$PATH
To append a new path, we reassign PATH with our new path at the end:

export PATH=$PATH:/some/new/path
4. Persisting Changes
When we use the export command and open a new shell, the added path is lost.

4.1. Locally
To persist our changes for the current user, we add our export command to the end of ~/.profile. If the ~/.profile file doesn’t exist, we should create it using the touch command:

touch ~/.profile
Then we can add our export command to ~/.profile.

Additionally, we need to open a new shell or source our ~/.profile file to reflect the change. We’d either execute:

. ~/.profile
or we could use the source command if we are using Bash:

source ~/.profile
We could also append our export command to ~/.bash_profile if we are using Bash, but our changes will be not be reflected in other shells, such as Z shell (zsh). We shouldn’t add our export command to ~/.bashrc because only interactive Bash shells read this configuration file. If we open a non-interactive shell or a shell other than Bash, our PATH change will not be reflected.

4.2. Globally
We can add a new path for all users on a Unix-like system by creating a file ending in .sh in /etc/profile.d/ and adding our export command to this file.

For example, we can create a new script file, /etc/profile.d/example.sh, and add the following line to append /some/new/path to the global PATH:

export PATH=$PATH:/some/new/path
All of the scripts in /etc/profile.d/ will be executed when a new shell initializes. Therefore, we need to open a new shell for our global changes to take effect.

We can also add our new path directly to the existing PATH in the /etc/environment file:

PATH=:/some/new/path
The /etc/environment file is not a script file—it only contains simple variable assignments—and is less flexible than a script. Because of this, making PATH changes in /etc/environment is discouraged. We recommend adding a new script to /etc/profile.d instead.

5. Conclusion
In this tutorial, we saw how Linux uses the PATH variable to find executables when running a command.

We can prepend or append to PATH, but we must persist these changes in ~/.profile. We can use ~/.bash_profile as well, but ~/.profile is preferred.

We can also change the global PATH value by adding our export command to a new .sh file in /etc/profile.d.

original link: https://www.baeldung.com/linux/path-variable