How to use Telnet in Linux

Telnet is a network protocol used to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. Here’s how you can install and use Telnet on a Linux system. I had to take a long walk in NYC before taking on this one. I assumed Telnet was no longer in use by anybody. …

Docker CLI basic commands

Docker is like a virtual box that lets you put your app inside and run it without worrying about messing up your computer. It’s like having a bunch of separate little rooms where you can run different apps at the same time without them bothering each other. Each room (or container) is lightweight and has …

Print the email addresses with status=”bounced” in postfix mail log

To print the email addresses with status “bounced” only from the provided log file, you can use grep to filter lines containing “status=bounced” and then use awk to extract the email addresses. Here’s how you can do it: Explanation: This series of commands will extract and print only the email addresses from lines with status …

How to use pflogsumm command to analyze postfix logs

To use the pflogsumm command to find general rejection reasons in your mail logs, you need to ensure that your mail server logs contain the necessary information about rejected or bounced emails. Once you have the logs, you can use pflogsumm to analyze them and generate a summary report that includes rejection reasons. Here’s how …

Clean System Data storage using macOS Terminal

The other day a client contacted me panicking about one his new macOS running out of disk space. He told me his System Data storage shows over 300GB of space. I quickly remembered a related issue on older macs on how to clean system data storage using the terminal. I quickly put my moka pot …

Update macOS from Terminal

After another snow day in NYC a customer contacted me about not being able to push macOS updates using his MDM provider. Why is the MDM provider not working? Their support was not that helpful and they blamed Apple for the updates not working. Then I said to myself “update macos from terminal?” Yes, I …

Find macOS version using the Terminal

I like to use the Terminal for most of my work and to find macOS version is quite simple. I help most of my clients remotely and using the Terminal is usually fast and simple in my opinion. As usual, I need to brew a great cup of coffee at home before taking on any …

4 ways to run Linux Commands in the Background

This is also another Linux command I tend to forget. I usually need to re-search how to run Linux commands in the background. This happens when I stop using the command line for a while. This time I’m going to write a brief Linux tutorial about this. First I need have brew a good cup …

Use the tar command to create/extract files in Linux

Sometimes I struggle to remember basic Linux commands. For example, how to create a tar.gz file in the command line is one of them. Also, how to extract the contents of a tar.gz file or view the contents or how to use my camera for street photography in Brooklyn. We need to use our friendly …