Linux Sysadmin Commands Guide

Fri, 26 Sep 2025 10:00:00 +0100

Linux Sysadmin Commands Guide

Introduction

As a Linux system administrator, mastering essential commands is crucial for managing servers, monitoring systems, and troubleshooting issues. This guide covers fundamental Linux commands for system administration, focusing on user management, process control, network diagnostics, and system monitoring, with practical examples.

Prerequisites

A Linux system (e.g., Ubuntu, CentOS, or Debian).
Root or sudo privileges.
Basic familiarity with the terminal.

System Information

Hardware and System Overview

# Display system information
uname -a

# Show CPU details
lscpu
cat /proc/cpuinfo

# Display memory usage
free -h
cat /proc/meminfo

# List block devices (disks)
lsblk
fdisk -l # Requires sudo

# Show mounted filesystems
df -h

System Uptime and Load

# Display system uptime and load average
uptime

# Show load average
cat /proc/loadavg

# Interactive system monitoring
top
htop # If installed

User and Group Management

Managing Users

# Add a new user
sudo useradd -m -s /bin/bash username

# Set a password for the user
sudo passwd username

# Modify user details
sudo usermod -aG groupname username # Add user to a group
sudo usermod -s /bin/zsh username # Change shell

# Delete a user
sudo userdel -r username # Remove user and home directory

Managing Groups

# Create a new group
sudo groupadd groupname

# Add user to a group
sudo usermod -aG groupname username

# List groups
getent group

# Delete a group
sudo groupdel groupname

Example: Creating a User with Specific Permissions

Create a user devuser with sudo privileges:

System-Administration on Manzolo Code Notes

Linux Sysadmin Commands Guide

Linux Sysadmin Commands Guide

Introduction

Prerequisites

System Information

Hardware and System Overview

System Uptime and Load

User and Group Management

Managing Users

Managing Groups

Example: Creating a User with Specific Permissions