Introduction

This guide provides a comprehensive overview of essential network and system commands used for monitoring, troubleshooting, and managing Linux systems. These commands help you gather information about network interfaces, active connections, system resources, and more.

Network Commands

Display Network Interface Information for All Interfaces

To display detailed information about all network interfaces:

ifconfig -a

List All Active Network Connections (TCP and UDP)

To view all active network connections, including TCP and UDP:

netstat -a

List Active TCP Connections

To view only active TCP connections:

netstat -at

Display Network Statistics for Ports

To show network statistics related to ports:

netstat -s

Perform DNS Lookup for a Domain Name

To perform a DNS lookup for a specific domain:

nslookup example.com

Perform DNS Query Using the dig Command

To query DNS records for a domain:

dig example.com

System Commands

Display System Uptime

To show how long the system has been running:

uptime

Display Who Is Currently Logged In and What They Are Doing

To view a list of logged-in users and their activities:

w

Display System Resource Usage, Processes, and Their Resource Consumption

To display system resource usage and active processes:

top

For an enhanced view with a more user-friendly interface:

htop

Display System Memory Usage

To view current memory usage:

free -h

List Open Files and the Processes That Opened Them

To list all open files and their associated processes:

lsof

List Block Devices (Disk Drives and Partitions)

To list all block devices, such as disks and partitions:

lsblk

To view block device information including filesystem types:

blkid

Display System Information, Including the Kernel Version

To show detailed system information and kernel version:

uname -a

To display the system hostname:

hostname

To display the current user:

whoami

To display user and group ID information:

id

Display Information About the Operating System Distribution

To show details about the operating system distribution:

cat /etc/os-release

List All Running Processes

To list all currently running processes:

ps

List All Processes (Including Those Owned by Other Users)

To list all processes, including those owned by other users:

ps -a

List Processes in a Tree-Like Format

To view processes in a hierarchical (parent-child) format:

ps -jT

List Background Jobs

To list jobs running in the background:

jobs

Check for Running Processes Containing "php" in Their Names

To find running processes with "php" in their names:

ps -f | grep php

Display System Hostname and Related Information

To view the system hostname and related settings:

hostnamectl status

Conclusion

These commands are essential for managing and troubleshooting Linux systems. They provide valuable insights into network status, system resource usage, and active processes, helping you effectively monitor and maintain your system.

This guide covers a range of commands to help you manage and troubleshoot Linux systems, including network-related commands, system resource commands, and process management commands.