Linux

Introduction

The “Out of Memory” (OOM) error in Linux can cause processes to crash or the server to become unresponsive. This guide shows you how to diagnose and fix OOM errors to keep your system stable.

Step-by-step Guide

1. Check system logs for OOM events
   • dmesg | grep -i oomn
     • or
     • grep -i 'killed process' /var/log/syslog

Reco

Introduction

rsync is a powerful and efficient tool for backing up and synchronizing files and directories in Linux. This guide shows you how to install rsync and use it for local and remote backups.

Step-by-step Guide

1. Install rsync
   • sudo apt update
   • sudo apt install rsync

Re

Introduction

Adding new users in Linux is essential for managing access and security on your server. This guide shows you how to create a new user, set a password, and assign permissions.

Step-by-step Guide

1. Add a new user
   • sudo adduser newusernamen
     • (Replace newusername with the desired username)

Introduction:
“Permission Denied” is a common error in Linux. Here’s how to fix it.

Steps:

1. Check file permissions:n
   • ls -l filename
   • Change permissions:n
     • sudo chmod 644 filename

Recommendations:

• ever use chmod 777 unless necessary.
• Use sudo for admin tasks.

Introduction

Docker makes it easy to deploy and manage applications in containers. This guide shows you how to install Docker on your VPS quickly and securely.

Step-by-step Guide

1. Update your package list:
   • sudo apt update

Introduction:
Enabling the firewall in Ubuntu with UFW (Uncomplicated Firewall) is a simple way to protect your server from unwanted access.

Step-by-step Guide:

1. Install UFW (if not already installed):n
   • sudo apt update
   • sudo apt install ufw

Recommendations:

• Only allow necessary ports.

Introduction:
Changing the default SSH port in Linux is a simple way to improve your server’s security and reduce brute-force attacks.

Step-by-step Guide

1. Open the SSH configuration file:
   • sudo nano /etc/ssh/sshd_config
   • Find the line:n
     • #Port 22

Introduction:
Forgot your Linux password? Don’t worry! Here’s a quick way to reset it using single-user mode.

Step-by-step Guide:

1. Reboot your server.
2. At the GRUB menu, select your Linux entry and press e to edit.

Recommendations:

• Use a strong password.