On CentOS and RHEL, you can check if the system needs a full reboot by checking the kernel version and the kernel release. A full reboot is required when the running kernel version and release are different from the latest installed kernel version and release. You can check the running kernel version and release by … Read more
To configure Amazon Web Services (AWS) Simple Email Service (SES) with the Postfix Mail Transfer Agent (MTA) on FreeBSD, you will need to follow these steps: Install the Postfix MTA by running the command “pkg install postfix”. Configure the Postfix MTA by editing the “/usr/local/etc/postfix/main.cf” file. Set the “myorigin” parameter to your domain name, set … Read more
To save iptables firewall rules permanently on Linux, you can use the iptables-save and iptables-restore commands. Start by saving your current iptables rules by running the following command: sudo iptables-save > /etc/iptables/iptables.rules This command will save the current iptables rules to a file named “iptables.rules” in the “/etc/iptables” directory. To make sure that the iptables … Read more
On Linux systems using systemd, you can use the “systemctl” command to view the status of a service. The basic syntax for the command is: systemctl status [service_name] For example, to check the status of the Apache web server, you can use the command: systemctl status httpd This command will return the current status of … Read more
Less is a command-line tool that allows you to view text files in a paginated manner. You can install it on CentOS, RHEL, and Fedora using the package manager. (https://www.fi-di.com/) To install less on CentOS or RHEL: Run the command “sudo yum install less” to install the less package. To install less on Fedora: Run … Read more
In Linux, you can write the output of a command to a file using the “>” operator. The basic syntax is: command > file For example, if you want to write the output of the ls command to a file named “list.txt”, you would run the following command: ls > list.txt This will create a … Read more
To set or change the Fully Qualified Domain Name (FQDN) on Ubuntu 20.04, you can follow these steps: Open the terminal by pressing “Ctrl + Alt + T” or by searching for “terminal” in the start menu. Run the command “sudo nano /etc/hostname” to open the hostname configuration file in nano text editor. Change the … Read more
To add days to a date and get the new date on Linux, you can use the date command along with the + operator. The basic syntax for adding days to a date is: date -d “current date + number of days” For example, to add 7 days to the current date, you would run … Read more
Ubuntu 20.04 includes a built-in tool called “unattended-upgrades” that allows you to set up automatic updates. Here’s how you can set it up: First, install the package by running the command “sudo apt install unattended-upgrades” Next, configure the package by editing the “/etc/apt/apt.conf.d/50unattended-upgrades” file. In this file, you can set the parameters for the automatic … Read more
You can check the expiration date of a TLS/SSL certificate from the command line using the “openssl” tool. Here’s an example command that checks the expiration date of a certificate for the domain “example.com”: openssl s_client -connect example.com:443 -servername example.com 2>/dev/null | openssl x509 -noout -dates The “-connect” option specifies the domain and port to … Read more