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Fred's Blog about Ham Radio, Python, Unix and more...

Arduino Temperature and Humidity sensor

This project will show the temperature in C and % of relative humidity of the ambient air on an LCD display.

Using SSH with an SSH bastion

One of the tasks of system administrators is to secure the machines inside of their network. To do so you usually configure access lists on your router to prevent access from the outside. If all the ports are blocked the system administrators won't be able to connect to the port …

Exim Vacation messages

I don't really understand why people love so mush auto-responders, especially business people. These messages add a considerable amount of useless noise in our mailboxes. Even though I dislike those emails, it doesn't prevent companies or friends I am hosting on my servers to request them. One of those companies …

Heartbeat Code For Cluster Environment

Working in a cluster environment, I often need to check if some of the nodes of my cluster are dead or live. To do so, I have a class called Heartbeat in my Python toolbox. This simple heartbeat class does a ping on the cluster node, and returns True, or …

Print system messages on an LCD display

At work, I manage a cluster of several hundred nodes. All those nodes are equipped with a little LCD display, like to one showed in the picture on the right. Until now, these displays were only displaying the name of the cluster vendor at boot, and the node name when …

Prime numbers using python generators

The Sieve of Eratosthenes is a fast and simple algorithm to generate all the primes in a range.

Growable Mac disk image

One of the features I like on my MacOS is the Support for SPARSE devices. Specifying -type SPARSE creates a disk image which expands as it is filled with data.