Linux

System Information

Command	Description
uname -a	Display Linux system information
top	Show system resource usage and running processes
free	Display available memory and swap space
df -h	Show disk space usage
du -sh	Show size of a directory
uptime	Show system uptime

User Management

Command	Description
useradd	Create a new user
passwd	Set user password
usermod	Modify user account
userdel	Delete a user
su	Switch user
sudo	Execute a command as a superuser
chown	Change file ownership
chgrp	Change file group ownership
chmod	Change file permissions

File Management

Command	Description
ls	List directory contents
cd	Change current directory
pwd	Print working directory
mkdir	Create a new directory
touch	Create a new empty file
cp	Copy files or directories
mv	Move or rename files or directories
rm	Remove files or directories
ln	Create a symbolic link

Text Editing

Command	Description
nano	Simple text editor
vi	Advanced text editor
sed	Stream editor
grep	Search for a pattern in a file or input
awk	Text processing and pattern matching

Network Management

Command	Description
ping	Check network connectivity
traceroute	Show the route packets take to a network host
netstat	Show network connections and statistics
ifconfig	Configure network interfaces
route	Show or modify the IP routing table
iptables	Configure firewall rules
ssh	Securely connect to a remote system

Process Management

Command	Description
ps	Show running processes
kill	Terminate a process
nice	Set process priority
nohup	Run a command that persists even if the terminal is closed
screen	Create a virtual terminal session
bg	Run a command in the background
fg	Bring a command running in the background to the foreground
jobs	List all background jobs

Package Management

Command	Description
apt-get	Install or remove software packages
dpkg	Install or remove individual software packages
yum	Install or remove software packages (Red Hat-based systems)
rpm	Install or remove individual software packages (Red Hat-based systems)

System Administration

Command	Description
cron	Schedule recurring tasks
systemctl	Manage system services (systemd-based systems)
service	Manage system services (init-based systems)
hostname	Set or display the system hostname
date	Display or set the system date and time
reboot	Reboot the system
shutdown	Shut down the system
tar	Create or extract tar archives

Miscellaneous

Command	Description
echo	Display a message on the terminal
history	Show command history
clear	Clear the terminal screen
whoami	Display the current user name
uname	Show system information
man	Show the manual for a command
which	Show the location of a command
whereis	Show the location of a command and its documentation
find	Search for files or directories
du	Show disk usage of files or directories
id	Display user and group information
time	Measure the time it takes for a command