topics/10-cheat-sheet

Cheat Sheet

Every essential command, one page. Bookmark it, or print it and pin it above your desk.

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Navigation & files

Command	What it does
pwd	Show the folder you're currently in
ls / ls -la	List files · detailed list incl. hidden ones
cd folder / cd .. / cd ~	Enter folder · go up one level · go home
mkdir -p a/b	Create folder(s), parents included
rmdir folder	Remove an empty folder
cp a b / cp -r dir dst	Copy a file · copy a folder recursively
mv a b	Move or rename files/folders
rm file / rm -r dir	Delete a file · delete a folder (no trash!)
touch file	Create an empty file (or update its timestamp)
cat file / less file	Print whole file · scroll through it (q quits)
head file / tail -f log	First 10 lines · last 10 lines, live-following

Search & help

Command	What it does
man ls	Full manual page for a command
ls --help	Quick built-in summary
grep -i "error" file	Find text in a file, ignoring case
grep -r "todo" ~/code	Search text in every file of a folder
find ~ -name "*.pdf"	Find files by name pattern
which python3	Where a command's program lives
history	Your recently typed commands

System info

Command	What it does
uname -r / uname -a	Kernel version · full system info
df -h	Free disk space, human-readable
du -sh folder	Total size of a folder
free -h	RAM usage
top / htop	Live process list (q quits)
whoami / who	Your username · who's logged in
uptime	How long since last reboot

Permissions & admin

Command	What it does
sudo cmd	Run one command as root (asks your password)
sudo !!	Re-run the previous command, but with sudo
chmod +x script.sh	Make a script executable
chmod 644 file	Owner: read+write · everyone else: read
chmod 600 key	Owner-only access (SSH keys, secrets)
chown alex file	Change a file's owner

Remember the permission math: r=4, w=2, x=1. So 7 = rwx, 6 = rw-, 5 = r-x, 4 = r--.

Package managers compared

Manager	Family	Install	Remove	Update everything	Search
apt	Debian · Ubuntu · Mint	sudo apt install pkg	sudo apt remove pkg	sudo apt update && sudo apt upgrade	apt search x
pacman	Arch · Manjaro	sudo pacman -S pkg	sudo pacman -Rns pkg	sudo pacman -Syu	pacman -Ss x
dnf	Fedora · RHEL	sudo dnf install pkg	sudo dnf remove pkg	sudo dnf upgrade	dnf search x
flatpak	Universal	flatpak install app	flatpak uninstall app	flatpak update	flatpak search x
snap	Universal (Ubuntu default)	sudo snap install app	sudo snap remove app	sudo snap refresh	snap find x

Where things live

Path	What lives there
/home/you	Your files & personal settings — your kingdom
/etc	System-wide configuration files
/var/log	System and app logs — first stop when debugging
/usr/bin	Installed programs
/tmp	Temporary files (cleared on reboot)
/root	Root user's home — locked to you
/media / /mnt	Where USB drives appear

Terminal superpowers

Shortcut	Magic
Tab	Autocomplete commands, files and folders
↑ / ↓	Walk through your command history
Ctrl + C	Stop a running command
Ctrl + L	Clear the screen
Ctrl + R	Search your history interactively
Ctrl + Shift + C / V	Copy / paste in most terminals
exit	Close the shell