ESXi is popular hypervisor product from VMware. It comes with several management GUIs including Vsphere and VCenter. Command line tools are also bundled, though they are used more rarely. This article describes a short script to list all virtual machines on the system.
The script is below. It is intended to run under the Busybox shell, the default environment when you ssh directly into the system hosting ESXi. Continue reading
This article presents a few informal benchmarks comparing the Raspberry Pi to the Raspberry Pi 2. The original Pi has a single core ARM v6 processor. The Pi 2 is quad core, ARM v7, and clocked faster than the Pi 1. But is it really six times as fast, as the makers claim ? Short answer: yes it is. And then some. Continue reading
The Raspberry Pi’s low power consumption makes it well suited to the role of always-on server. This post describes how to install Owncloud onto the Pi. Owncloud is an open source software package providing remote file sharing services, similar to Dropbox. But with Owncloud, you retain ownership, security and control of the shared data. Owncloud works well on a Pi 2 and Pi 3 but will run very slowly on a Pi 1.
Update 20th November 2016 – There is a newer version of this article. Please see Simple Nextcloud Installation on Raspberry Pi. Nextcloud was forked from ownCloud in June 2016. It now seems to have become the natural successor to Owncloud. I recommend using Nextcloud rather than Owncloud. This article remains on line because it might be helpful to existing Owncloud users, particularly the parts about upgrading and using external USB media.
UPDATE 16th July 2016 – Nextcloud was forked from Owncloud in June 2016. The procedure below can be used both for Owncloud and the initial release of Nextcloud (version 9.0.52). Thanks to Dan for this information.
My Raspberry Pi 2 was purchased from RS Components in the UK. It was installed with Raspbian “Jessie” (Debian 8) by applying the image “2016-02-09-raspbian-jessie.img” downloaded from the raspberrypi.org downloads page. The following procedure was then performed without any further pre-work (other than enabling ssh in the basic setup). Continue reading
Here is a tip for speeding up WordPress, especially if you are running it on a low power server. I made the change to WordPress running on a small ARM server, resulting in an immediate and dramatic speed up. It works because it prevents bots on the Internet from wasting your server resources. Continue reading
This article explains how to send email from the Raspberry Pi. It is a generic procedure and also works on other Debian distributions. This is not for receiving mail, only for sending it. (Receiving email on the Pi is a much more involved process, requiring your Pi to perform the role of a full mail server).
The ability to send mail across the Internet is useful. It enables scripts and applications to send you email about system events or the sending data such as pictures from a webcam.
This article was updated in December 2019 and has been successfully tested on Raspbian Stretch, Jessie and Buster/Debian 10.
Continue readingThis article discusses some of the caption and border effects available with the ImageMagick image processing package. ImageMagick is freely available for Linux and Windows. It offers a huge number of image processing options, so many in fact, that using the program can be a little tricky.
The following examples were evolved from the ImageMagick online documentation, plus a good deal of trial and error to get the details right. I used Linux, but the same commands should work under Windows. Continue reading
The Raspberry Pi is a small Linux computer designed to help children learn programming. Being a full Linux System, it can also be used as a server or as the basis for various projects. The Pi’s low power consumption makes it particularly suited to the role of always-on web server.
This post describes how to create a simple photo gallery on the Pi, which can be shared over the internet with or without password protection. While not as polished as Flickr, Smugmug or similar services, it allows you to retain ownetship, control and security of the shared images. Continue reading
Here is a quick fix that might help users experiencing the “no devices available” problem when using xsane, the Linux scanning tool.
In this case, the device was an HP 3070 B611, a combined printer and scanner. The OS (Fedora 20) was able to see the device as a printer and print okay, but the scanner part did not work. Xsane just popped a small window saying unable to find device.
The fix was a change in the CUPS configuration, and it may therefore work with other versions of Linux.
Note: (19th June 2016) This article receives an unexpectedly large number of hits. If you have come here expecting something else, for example information about network scanners like nmap or Wireshark, please leave a comment to that affect and I will adjust the keyword settings. This article is about document scanners, not software to snoop your LAN.
This article was rewritten and updated on 9th April 2017.
BT is a popular Internet service provider in the UK. BT subscribers receive a free router called the “BT Home Hub“. A new model of Home Hub is launched every few years, and as BT never takes the old ones back, many people have an old Hub tucked away somewhere, gathering dust.
This post explains how to convert an old BT Home Hub 5.0 or Home Hub 4.0 into a second wireless access point (“AP”) on your network, strengthening and extending the wireless signal around your home or office. Although the details are for those routers, the basic procedure works for other BT and perhaps non-BT routers. In particular, notes have been included for the BT Home Hub 3.0 and the now ancient Home Hub 1.0 – these are indented and written in italics. Many users have also had success in reusing Home Hub models 2.0 and 6.0 (BT’s latest router, also known as the Smart Hub). Continue reading
This post shows how to use parallel processing to get a CPU intensive job done faster in Unix/Linux. By splitting a large task into several parts, it is quite easy to give each part to a separate CPU, and complete the task many times faster than it would on a single processor.
These days, even small PCs and other devices often come equipped with several CPU cores. But some tasks will use only one core, sometimes using 100% of it, while other cores stand by idle. Sometimes this is a waste of resources. Continue reading