ncdu - Better version of du that provides a navigation interface. Allows navigation, deleting of files, sorting by file names / sizes etc. Read more at: https://linux.die.net/man/1/ncdugetent group <x> - Get list of all members in group <x>ifconfig - Deprecated. Use ip addr insteadip addr - Alternative to inconfig. Allows addition/deletion of ips. Read more at: https://linux.die.net/man/8/iplastb - Gives a list of all failed loginsfail2ban - Is a service to prevent malicious logins (Read more at: https://www.fail2ban.org/wiki/index.php/Main_Page)fail2ban-client status sshd - Will give stats about failed loginslast reboot - Prints list of past rebootsnetplan apply - Applies the network configuration defined in /etc/netplan/...yamllsblk - List block devices. Read more at: https://linux.die.net/man/8/lsblkdmidecode - Software tool that allows you to extract detailed hardware information from a system by decoding the DMI (Desktop Management Interface). Read more at https://www.howtoforge.com/dmidecode-finding-out-hardware-details-without-opening-the-computer-case
Commonly used dmidecode -t system and dmidecode -t baseboardlsb_release -a - Shows current version of the OS#!/bin/bash -e - The 'shebang' that you add to the top of a bash script such that the script exits when any line in the script returns with a non-zero exit statusdo-release-upgrade - Upgrades the OS to latest developmental release. This is NOT a CLEAN INSTALL. It will upgrade the existing OS that’s all!dmesg - https://www.howtogeek.com/449335/how-to-use-the-dmesg-command-on-linux/modprobe - Used to add or remove modules from the kernel. Read more at https://www.linuxfordevices.com/tutorials/linux/modprobe-command and https://linux.die.net/man/8/modprobesystemctl - CLI utility to manage services without using SystemD. Read more at: https://man7.org/linux/man-pages/man1/systemctl.1.html
systemctl list-units - Lists units that systemd currently has in memory. Includes units directly referenced or through a dependency.