Linux commands you should know

Here are some Linux commands you might want to know.

Basics

whoami: a philosophical question, also prints current username
id: prints current user information (e.g., username, UID, GIDs)
pwd: print working directory (or use echo $PWD)
sudo COMMAND: run command as root
- Only users and groups in the sudoers file can run sudo. Check if you have sudo permissions with sudo -l.
sudoedit FILE: edit file as root with your favorite EDITOR (make sure to export EDITOR=insert-your-favorite-editor first)
apt: package management system on Debian-based distros (or use dpkg if you ever need to)
bash: The de facto default shell. You might want to learn Bash script.
passwd: change your user password
man: manual. For example, if you need to look up what abs() is, run man abs. Don’t look up “man abs” like my teammate did.
curl URL or wget URL: download stuff from the interwebs without a browser
ssh USER@HOST: remotely access a computer running an SSH server
systemctl: Chances are your distro runs systemd. You might want to learn what it does.
ps & top (& htop / btop): show processes
open / xdg-open: open stuff (e.g., files) with the right program

ls [ DIR ]: list files in a directory (defaults to current directory)
cd [ DIR ]: change working directory (defaults to home)
mv A B
- if B doesn’t exist, rename A to B
- if B exists and is a file, delete B and rename A to B
mv A... B: move files to B (B must be a directory)
rm FILE: remove a file
rm -r DIR: remove a directory
sudo rm -rf --no-preserve-root /: fries your system (please don’t actually run it)
sudo dd if=random-linux-distro.iso of=/dev/sdX: makes a bootable USB using ISO (be very certain that of is set to the right device file)
for d in /dev/nvme0n1p*; do sudo dd if=/dev/zero of=$d; done: fries your system with SPEED (please don’t actually run it)
lsblk: show block devices
rmdir DIR: remove an empty directory
grep: search for something (string or regex) in a file or directory. Use grep PATTERN FILE and not cat FILE | grep PATTERN.
find: find files on the filesystem
locate: find files on the filesystem quickly using an index (use updatedb to refresh the index; you can do it in a systemd timer)

nano FILE: edit FILE in a user-friendly terminal editor
vim FILE: edit FILE in a user-unfriendly terminal editor that you don’t know how to exit
emacs -nw FILE: edit FILE in a user-unfriendly terminal editor that gives you pinky cancer (evil mode FTW). See Emacs.
ed: Yes, this is a text editor. Hope you never have to use it.
code [ FILE | DIR ]: edit file / open directory with Visual Studio Code (not necessarily a Linux command per se)

ip / ifconfig: show networking device information (e.g., private IP addresses)
ss / netstat: show socket statistics (e.g., open ports)
nmap: enumerate ports on a host, or hosts on a network
nmcli: Network Manager CLI
sudo systemctl restart NetworkManager for when NM decides to give up