Linux Cheatsheet

Updated September 2026 · Quick reference

The shell lets you navigate the filesystem, manage files, and run programs with short commands.

Examples assume a common Bash-style environment. Check your distribution’s package manager if a command name differs slightly.

Full lessons: Linux Tutorials

Navigation

pwd

Print the current working directory—your location in the filesystem tree.

pwd

ls

List directory contents. Common flags: -l long format, -a include hidden, -h human sizes.

ls -lah
ls /var/log

cd

Change directory. ~ is your home; .. is the parent; - returns to the previous directory.

cd ~/projects
cd ..
cd -

Absolute vs relative paths

Paths starting with / are absolute from the root; others are relative to the current directory.

cd /etc
cd ../docs

clear / Ctrl+L

Clear the terminal screen so recent output is easier to read (history remains available).

clear

man

Open the manual page for a command. Quit with q; search inside with /.

man ls
man 5 passwd

Files

mkdir

Create directories. Use -p to create parent folders as needed.

mkdir notes
mkdir -p projects/web/css

touch

Create an empty file or update a file’s timestamp.

touch readme.md
touch notes/{a,b,c}.txt

cp

Copy files or directories. Add -r to copy directories recursively.

cp draft.txt draft.bak
cp -r site/ site-backup/

mv

Move or rename files and directories.

mv old-name.txt new-name.txt
mv report.pdf ~/Documents/

rm

Delete files. Use -r for directories and double-check paths—deletes are usually permanent.

rm temp.log
rm -ri old-folder/

ln -s

Create a symbolic link (shortcut) that points to another path.

ln -s ~/projects/app /var/www/app

Viewing & search

cat / less

cat prints a whole file; less pages through long output interactively.

cat notes.txt
less /var/log/syslog

head / tail

Show the beginning or end of a file. tail -f follows new lines as they are written.

head -n 20 access.log
tail -f app.log

grep

Search for text patterns in files. -i ignores case; -r searches recursively.

grep -i "error" app.log
grep -rn "TODO" src/

find

Locate files by name, type, or other tests under a starting path.

find . -name "*.py"
find /var/log -type f -mtime -1

Pipes & redirection

Pipe (|) sends stdout to another command; > writes a file; >> appends.

ls -1 | wc -l
grep fail app.log > failures.txt

du / df

du estimates directory disk use; df shows filesystem free space.

du -sh ~/Downloads
df -h

Permissions

Permission bits

Read, write, and execute for user, group, and others. Shown by ls -l as rwx triples.

ls -l script.sh
# -rwxr-xr-x  owner can rwx; group/others rx

chmod

Change mode bits symbolically or numerically (for example 755 or 644).

chmod u+x deploy.sh
chmod 644 config.ini

chown

Change file owner and optionally group. Often needs elevated privileges.

sudo chown alice:alice report.pdf
sudo chown -R www-data:www-data /var/www/html

whoami / id

Show the current username and numeric user/group IDs.

whoami
id

sudo

Run one command as another user (usually root). Prefer the least privilege that still works.

sudo apt update
sudo -u www-data ls /var/www

Packages & processes

apt update / install

On Debian/Ubuntu, refresh package indexes then install software.

sudo apt update
sudo apt install curl git

apt remove / search

Remove packages or search the package list by keyword.

apt search nginx
sudo apt remove unused-tool

ps / top

List running processes. top (or htop) updates interactively.

ps aux | grep python
top

kill / killall

Send a signal to a process (default TERM). Use the PID from ps carefully.

kill 12345
killall -TERM myapp

jobs / bg / fg

Manage jobs started in the current shell: list, resume in background, or bring to foreground.

jobs
bg %1
fg %1

systemctl (services)

On systemd systems, start, stop, and check service status.

systemctl status ssh
sudo systemctl restart nginx

Networking basics

ping

Send ICMP echo requests to test basic reachability and latency.

ping -c 4 example.com

ip / hostname

Show addresses and hostname. Many systems use ip instead of older ifconfig.

ip a
hostname -I

curl / wget

Download or request URLs from the command line. curl -I shows response headers.

curl -I https://example.com
wget https://example.com/file.zip

ssh

Open a secure shell session to a remote host. Keys are preferred over passwords.

ssh [email protected]
ssh -i ~/.ssh/id_ed25519 [email protected]

ss / netstat

Inspect listening ports and connections. ss is the modern default on many distros.

ss -tulpn
ss -tp | grep ssh

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