Basic System Commands

Command	Description
cat	displays the contents of a file
pwd	displays the current working directory
cd	changes the current directory
ls	lists the contents of a directory
cp	copies files and directories
mv	moves or renames files and directories
rm	removes files and directories
mkdir	creates a new directory
rmdir	removes an empty directory
chmod	changes the permissions of a file or directory
ps	displays information about running processes
top	displays real-time information about system usage
kill	terminates a process
shutdown	shuts down the system

File Commands

Command	Description
ls	lists the files of a directory
ls -l	lists the files of a directory in long format
ls -a	lists all files of a directory, including hidden
pwd	displays the current working directory
cd	changes the current directory
cd ~	changes the current directory to the home directory
cd ..	changes the current directory to the parent
cd -	changes the current directory to the previous
cd /	changes the current directory to the root
mkdir	creates a new directory with the specified name
rmdir	removes the directory with the specified name
touch	creates a new file with the specified name
cp	copies files and directories
mv	moves or renames files and directories
rm	removes files and directories
rm -r	removes files and directories recursively
rm -f	removes files and directories forcefully
rm -rf	removes files and directories forcefully recursively

File Permissions

Command	Description
chmod 777 file	Gives Read, Write and Execute permissions to everyone
chmod 755 file	Give read, write, and execute permission to owner, and read and execute permission to group and others
chmod 644 file	Give read and write permission to owner, and read permission to group and others
chown user file	changes the owner of a file
chown user:group file	changes the owner and group of a file
chmod u+x file	gives execute permission to the owner
chmod g+x file	gives execute permission to the group

Users and Groups

Command	Description
id	displays the user and group IDs
id user	displays the user and group IDs for a specific user
whoami	displays the current user
who	displays who is logged on
who -a	displays who is logged on and what they are doing
last	displays the last logged in users
adduser user	adds a new user
usermod -aG group user	adds a user to a group
groupadd group	adds a new group
userdel user	deletes a user
usermod	modifies a user account
chgrp group file	changes the group ownership of a file

Package Management (Needs sudo)

Command	Description
apt update	updates the package lists
apt upgrade	upgrades the installed packages
apt install package	installs a package
apt remove package	removes a package
apt autoremove	removes packages that are no longer needed
apt search package	searches for a package
apt purge package	removes a package and its configuration files
apt clean	removes downloaded package files
apt autoclean	removes old downloaded package files

SSH

Command	Description
ssh user@host	connects to a remote host using SSH
ssh -p port user@host	connects to a remote host using SSH on a specific port
ssh-keygen	generates a new SSH key pair
ssh-copy-id user@host	copies the SSH key to the remote host
ssh -i key user@host	connects to a remote host using a specific SSH key
scp file user@host:	copies a file to a remote host

System Info

Command	Description
uname	print system information
uname -a	displays all system information
uname -r	displays the kernel release
uname -m	displays the machine hardware name
uname -n	displays the network node hostname
hostname	displays the network node hostname
hostname -I	displays All IP address
uptime	displays how long the system has been running
whoami	displays the current user
df	displays the amount of disk space available
man	displays manual page

Privilege Escalation

Command	Description
sudo	allows a user to execute a command as the superuser
su	allows a user to execute a command as another user
sudo su	allows a user to execute a command as the superuser
sudo -i	allows a user to execute a command as the superuser
sudo -u	allows a user to execute a command as another user
sudo -l	allows a user to list the allowed commands

Archiving

Command	Description
tar -cvf archive.tar	creates a new archive
tar -xvf archive.tar	extracts files from an archive
tar -tvf archive.tar	lists the contents of an archive
tar -cvzf archive.tar.gz	creates a new compressed archive
zip archive.zip file	creates a new archive in ZIP format
unzip archive.zip	extracts files from an archive in ZIP format

Searching

Command	Description
grep pattern file	searches for a pattern in a file
grep -r pattern dir	searches for a pattern in a directory recursively
grep -v pattern file	searches for all lines that do not contain a pattern
grep -i pattern file	searches case-insensitively for a pattern in a file
grep -l pattern file	displays the names of files that contain a pattern
locate file	searches for a file in the database
find dir -name file	searches for a file in a directory
find .	searches for files in the current directory
find / -name file	searches for a file in the entire system
find / -name file -type f	searches for a file in the entire system for file types

Process Management

Command	Description
ps	displays your currently active processes
ps -ef	displays all processes
top	displays all processes
kill pid	kills the process with the specified process ID
killall process	kills all processes with the specified name
bg	List and resume stopped jobs in the background
fg	Bring the most recently suspended job to the foreground

Networking

Command	Description
ifconfig	displays the network interfaces
ifconfig -a	displays all network interfaces
ifconfig eth0	displays the network interface eth0
iwconfig	displays the wireless network interfaces
systemctl stop NetworkManager	stops the NetworkManager service
systemctl start NetworkManager	starts the NetworkManager service
systemctl restart NetworkManager	restarts the NetworkManager service
whois domain	displays whois information for a domain
dig domain	performs DNS lookup for a domain
host domain	performs DNS lookup for a domain
nslookup domain	performs DNS lookup for a domain
ping domain	pings a domain and displays the result

Keyboard Shortcuts

Command	Description
Ctrl + C	Stops the current command
Ctrl + Z	Backgrounds the current command
Ctrl + D	Logs out the current user
Ctrl + A	Moves the cursor to the beginning of the line
Ctrl + E	Moves the cursor to the end of the line
Ctrl + L	Clears the terminal screen
Ctrl + Shift + C	Copies the selected text
Ctrl + Shift + V	Pastes the selected text
Ctrl + Shift + T	Opens a new tab in the current window
Ctrl + Shift + N	Opens a new window in the current session
Ctrl + Shift + Q	Closes the current window
!!	Repeats the previous command
exit	Exits the current shell