John's Linux blog

# Create a directory structure mkdir inventory_app cd inventory_app # Create app.py, requirements.txt, and Dockerfile touch app.py requirements.txt Dockerfile # Build the Docker image using the standard Python 3.11 image docker build -t inventory-app:full . # Display Docker images docker images # Rewrite the Dockerfile to use the lightweight Python 3.11-slim image # (Edit Dockerfile content accordingly) # Build the Docker image using the slim image docker build -t inventory-app:slim . # Display Docker images again docker images https://www.kdnuggets.com/how-to-create-minimal-docker-images-for-python-applications

Normally to get the disk usage of a folder you use get properties on the rightclick or similar. However there are hidden files starting with . in their name that you can get info on, only in the terminal, using the  du -sh  command. If you have hundreds of them (which you do!) this becomes tedious. The following script gives you a directory listing with the files all indicated in file sizes and highlights on files of megabytes or gigabytes in size.  #!/bin/bash # Set Internal Field Separator to handle spaces in filenames IFS=$'\n' # Loop through all files and directories for i in $(/bin/ls -A); do        size=$(du -sh "$i" | awk '{print $1}')           # Apply colors: bold for MB, bright bold for GB      case "$size" in          *M) color="\e[1m" ;;         # Bold for Megabytes          *G) color="\e[1;97m" ;;      # Br...

Sometimes the Gnome Shell dock (application launcher strip) goes blank. To get it back without logging out and back in: Press Alt + F2 Type r Press Enter This will restart GNOME Shell while keeping your applications running. To do this in a shell script: #!/bin/bash dbus-send --type=method_call --dest=org.gnome.Shell /org/gnome/Shell org.gnome.Shell.Eval string:'global.reexec_self()'

 My own script: #!/bin/bash echo "Resource Usage Report" echo "=====================" # Top 3 CPU consumers echo "CPU:" ps -eo pid,comm,%cpu --sort=-%cpu | head -n 4 | awk 'NR>1 {printf "- %s: %s%%\n", $2, $3}' # Top 3 Memory consumers echo "RAM:" ps -eo pid,comm,%mem --sort=-%mem | head -n 4 | awk 'NR>1 {printf "- %s: %s%%\n", $2, $3}' # Top 3 Disk IO consumers echo "Disk:" iotop -b -n 1 | head -n 12 | grep -E '^ *[0-9]' | awk '{printf "- %s: %s%%\n", $12, $10}' | head -n 3 1. iostat (from the sysstat package) Use: Provides detailed statistics about CPU utilisation and I/O performance for devices and partitions. Why Use It: Focused on I/O bottlenecks. Breaks down performance metrics by individual devices (e.g., disks). Includes metrics like device utilisation, read/write speeds, and queue lengths. 2. iotop Use: Displays real-time I/O usage by processes. Why Use It:...

By default Ubuntu Linux does not copy the app launcher (dock-like thing) or the menubar to new screens (monitors). To do this you have to install some items. 1. Copy the Menubar to Another Screen/Monitor: Install GNOME Shell Extension: Multi Monitors Add-On : sudo apt install gnome-shell-extension-multi-monitors Enable the extension: gnome-extensions enable multi-monitors-add-on@spin83 Open GNOME Tweaks and enable the Multi Monitors extension under the "Extensions" tab. 2. Copy the App-Launcher/Dock-Like App to Another Screen/Monitor: Install Dash to Dock : sudo apt install gnome-shell-extension-dash-to-dock Enable Dash to Dock : gnome-extensions enable dash-to-dock@micxgx.gmail.com Configure Dash to Dock in GNOME Tweaks to display on multiple screens. However, spin83 (multimonitors) only works on old distros (it was released in 2014), so you need this version edited by myself:  https://github.com/JohnOstrowick/multi-monitors-add-on

To create DMARC, SPF, and DKIM records for your domain, you'll need to configure the DNS TXT entries for each. Here's how to do it: 1. SPF Record The SPF record helps to identify which mail servers are allowed to send email on behalf of your domain. Step-by-Step: Login to your DNS provider's management panel. Add a new DNS TXT record with the following value: v=spf1 a mx ip4:< myserver.net > -all 2. DMARC Record DMARC tells mail servers how to handle emails that fail SPF or DKIM checks. Step-by-Step: Add a DNS TXT record with the following value: v=DMARC1; p=none; rua=mailto:postmaster@myserver.net; ruf=mailto:postmaster@myserver.net; sp=none; aspf=r; This record means that DMARC is set to "none" (no enforcement). You can change p=none to p=quarantine or p=reject once you are confident your setup is working. 3. DKIM If you haven't installed OpenDKIM, do so: sudo apt-get update sudo apt-get install opendkim opendkim-tools Next, generate your DKIM key p...