linux

GNU/Linux

History

Started in 1983 by Richard Stallman, the GNU Project aimed to build a free Unix-like OS
By the early 1990s, GNU lacked a kernel until Linus Torvalds created the Linux kernel in 1991, released under the GNU GPL in 1992
Together, they formed GNU/Linux, a free, open-source alternative to proprietary Unix
GNU/Linux is packaged into user-friendly distributions like Ubuntu, Debian, and Fedora, each offering unique features and interfaces

Key features

Free and open-source, unlike paid Unix systems
GNU tools paired with the Linux kernel
Kernel manages CPU, memory, and storage
Distributions (e.g., Ubuntu for beginners, Debian for stability, Fedora for cutting-edge updates) make GNU/Linux accessible

Learn more

Fun fact: A directory is a just a file containing the names of other files

Category	Popular Commands
File System Navigation	cd, pwd, ls
File & Directory Mgmt	cp, mv, rm, mkdir, touch, ln -s
Viewing & Editing Files	cat, less, head, tail, nano, vim
Searching Files & Text	find, grep, locate, wc
Permissions & Ownership	chmod, chown, chgrp
Process Management	ps, top, htop, kill, killall
System Information	uname, uptime, df -h, du -sh, free -h
Hardware Information	lscpu, lsblk, lspci, lsusb
Networking	ping, ip/ifconfig, ssh, scp, wget, curl
Archiving & Compression	tar, gzip, gunzip, zip, unzip
Package Management	apt/dnf/yum/pacman (install, remove, update)
User & Group Management	sudo, su, useradd, usermod, passwd, whoami, id
Disk Management	lsblk, df -h, mount, umount, fdisk -l
System Services (systemd)	systemctl (start, stop, status, enable, disable)
Job Scheduling	crontab -e, crontab -l, at
Shell Environment	echo, export, alias, source, env
Command History & Help	history, man, --help, apropos
System Control	shutdown, reboot, clear, hostname
Development Tools	git, make, gcc/g++
Miscellaneous Utilities	watch, tee, sleep, which, type, xargs

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ssh

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telnet google 80

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man telnet

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telnet --help

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which telnet

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ls /usr/bin | grep telnet

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docker ps -a | awk 'NR>2 {print $2}'

Console

Physical devices to interact with the computer such as screen, keyboard, and mouse

Terminal

Shell