System Administration Development Tutorials, Guides & Insights

• Install multiple packages:

  sudo dpkg -i package1.deb package2.deb package3.deb

   sudo firewall-cmd --zone=public --remove-service=ssh --permanent
   sudo firewall-cmd --reload

• Add a Rich Rule:

To build a custom Docker image, you need to create a Dockerfile. Here's an example:

# Use an official Ubuntu as a parent image
FROM ubuntu:latest

# Install necessary packages
RUN apt-get update && apt-get install -y nginx

# Expose port 80
EXPOSE 80

# Start Nginx when the container launches
CMD ["nginx", "-g", "daemon off;"]

sudo apt-get update
sudo apt-get upgrade

To upgrade the distribution (e.g., from Ubuntu 20.04 to 22.04):

This command changes the owner and group of all files and subdirectories within directoryname.

• Setuid (Set User ID): When set on an executable file, this bit allows the file to be executed with the privileges of the file's owner.