In this post, How to use vlock command Lock Your Terminal Sessions on Linux. Keep your Linux safe from Prying eyes Use vlock command can keep unauthorized users from Linux command line.  vlock command is a command-line program that will lock your Linux terminal, as well as virtual consoles. Install vlock command on Linux On Debian/ Ubuntu : sudo apt install vlock   on an RHEL-based distro like Fedora or CentOS, vlock should be installed by default. If it isn't, your run command as below: sudo dnf install kbd Lock Your Terminal With vlock command vlock The display the message, "This TTY is now locked." To use your terminal, press Enter and vlock will prompt you for your password. Locking All Virtual Terminals on Linux With the -a or --all flag to lock all Virtual Terminal on Linux. vlock --all This will lock all the virtual terminals on your system

In this tutorial, How to Use whois Command on Linux WHOIS (pronounced as the phrase "who is") is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block or an autonomous system. Quota from Wikipedia Download and install Whois Linux command For Ubuntu, Linux Mint, ElementaryOS and Debian OS: sudo apt-get install whois For CentOS and RHEL: sudo dnf install whois The output terminal as below The syntax whois command whois domain whois public-ip-address whois [options] public-ip-address For example whois command whois huuphan.com whois 172.67.137.70 Getting help whois command $ man whois OR $ whois --help The output terminal as below