In this manual, you will find the essential commands to navigate and work in the terminal of a GNU/Linux system. It is a quick reference for both beginners and technical users.

Prerequisites

• Access to a Linux server.
• Terminal connection (local or via SSH).

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Navigation and file system

cd → Change directory

cd /
cd folder/subfolder
cd ..

pwd → Show current path

pwd

ls → List files

ls
ls *.txt

mkdir / rmdir → Create / delete directories

mkdir new_directory
rmdir new_directory

cp / mv → Copy and move files

cp file copy
mv file destination/

rm → Delete files

rm file
rm *

File viewing

cat, less, head, tail

cat file.txt
less file.txt
head file.txt
tail file.txt
tail -f log.txt

Permissions and owners

chmod → Change permissions

chmod 755 file
chmod u+x file

chown → Change owner

chown user:group file
chown -R user:group directory

System information

uname → System information

uname
uname -a

whoami → Current user

whoami

df / du → Disk usage

df -h
du -sh *

free → Memory usage

free -m

Search and filtering

find → Search for files

find -name file.txt

grep → Search inside files

grep 'text' file.txt

sort → Sort content

sort file.txt

Processes and system

ps → View processes

ps
ps -ef

kill → Terminate processes

kill PID

service → Manage services

service nginx start
service nginx stop
service nginx restart

Connectivity

ssh → Remote connection

ssh user@IP
ssh -p 2200 user@IP

Useful utilities

echo → Display text / write to file

echo 'Hello'
echo 'Hello' > file.txt

touch → Create empty file

touch file.txt

ln → Create link

ln file link

tar → Compress / decompress

tar cvf file.tar *.txt
tar xvf file.tar

watch → Run command periodically

watch -n5 'free -m'

Users and privileges

sudo → Run as administrator

sudo command

su → Switch user

su user

Terminal

clear → Clear screen

clear

Shortcut:

Ctrl + L

exit → Exit terminal

exit

💡 Practical tips

• Use the ↑ ↓ arrows to retrieve previous commands.
• Use man command to see help:

man ls

• Be careful with commands like rm * or chmod 777.