http://johnbokma.com/ John Bokma, a freelance Perl programmer http://johnbokma.com/blog/2020/09/28/rehousing-two-tarantulas.html I originally had planned to rehouse two of the tarantulas I keep yesterday. But when drilling holes in a plastic container to provide required ventilation it turned out that the battery of the drill was nearly empty. As charging takes a long time I decided to move the rehousing to Monday afternoon; today. [...] 2020-09-28T23:00Z http://johnbokma.com/blog/2020/03/28/perl-version-tumblelog-ubuntu-bionic-beaver-howto.html Earlier this week I was contacted by Paul N. Pace who had problems installing the Perl version of tumblelog on his Mint 19 installation which according to his email is based on Ubuntu 18.04 LTS. Because I am sure there are more people interested in this I decided to write a how to on the installation [...] 2020-03-28T23:00Z http://johnbokma.com/blog/2020/03/07/a-visit-to-avonturia-de-vogelkelder.html For today we had planned to pay a visit to Avonturia, also known as "De Vogelkelder" (The bird cellar) located in the city of The Hague. I had read on Facebook that they also sell tarantulas, and I wanted to buy like two or so to extend my collection to three; I bought a tiny Chromatopelma cyaneopubescens, [...] 2020-03-07T23:00Z http://johnbokma.com/blog/2019/11/08/flashing-a-tp-link-tl-wdr-4300-with-openwrt.html Today I flashed a TP-Link TL-WDR4300 with OpenWrt firmware using my 2014 Mac Mini running OS X Mojave. Below follow my notes. I highly recommend to read the official OpenWrt documentation as [...] 2019-11-08T23:00Z http://johnbokma.com/blog/2019/10/17/mounting-a-vdi-file-in-a-different-virtualbox-guest.html Today I wanted to check if a specific file was on an old Linux virtual disk image (VDI) I had on an external backup disk. I had already an Ubuntu guest up and running so I wanted to mount the VDI file located on the external harddisk as an additional virtual harddisk and access it from within the Ubuntu [...] 2019-10-17T23:00Z http://johnbokma.com/blog/2019/10/17/wireless-headless-raspberry-pi.html Today I set up a wireless, headless, Raspberry Pi 3B. This was easier than expected, it worked at the first try. The following instructions are for preparing an SD card on macOS for booting a headless and wireless [...] 2019-10-17T23:00Z http://johnbokma.com/blog/2019/10/09/rfc-822-and-rfc-3339-dates-in-python.html When adding a JSON feed and an RSS feed to tumblelog I needed a publication date and time for each article published. As I don't have an actual publication time I decided to use the end of day, as explained in A Matter of [...] 2019-10-09T23:00Z http://johnbokma.com/blog/2019/10/09/rfc-822-and-rfc-3339-dates-in-perl.html When adding a JSON feed and an RSS feed to tumblelog I needed a publication date and time for each article published. As I don't have an actual publication time I decided to use the end of day, as explained in A Matter of [...] 2019-10-09T23:00Z http://johnbokma.com/blog/2019/10/09/a-matter-of-time.html Several weeks ago, when I started to add a JSON feed to tumblelog I had to consider what time stamp to use for date_published. As I blog often more than once during the day, and all such entries end up on the same page, there is no specific publication time to assign to such a page. Well, technically [...] 2019-10-09T23:00Z http://johnbokma.com/blog/2019/10/09/hand-coding-an-rss-2-0-feed-in-python.html One requirement I have for tumblelog is that everything the Python version generates is identical to everything the Perl version generates. This means that sometimes I have to hand code a function that is available in a library for, say Python, but works differently in a Perl [...] 2019-10-09T23:00Z http://johnbokma.com/blog/2019/10/09/hand-coding-an-rss-2-0-feed-in-perl.html One requirement I have for tumblelog is that everything the Perl version generates is identical to everything the Python version generates. This means that sometimes I have to hand code a function that is available in a library for, say Python, but works differently in a Perl [...] 2019-10-09T23:00Z http://johnbokma.com/blog/2019/09/24/nav-element-with-no-heading.html Last Thursday, while playing with the W3C Markup Validation Service with as input my other blog, Plurrrr, I noticed twice the following remark in the Structural outline after I had selected Show Outline as an [...] 2019-09-24T23:00Z http://johnbokma.com/blog/2019/09/16/rewriting-commonmark-nodes-in-perl-right-this-time.html Although I thought I had found a solution to the memory corruption problem I ran into when rewriting CommonMark nodes in Perl testing my code in tumblelog showed this not to be the case. After some more experimentation and looking at the XS Perl module I gave up and contacted the author of the CommonMark [...] 2019-09-16T23:00Z http://johnbokma.com/blog/2019/09/12/rewriting-commonmark-nodes-in-perl.html Note: the solution given in this article still causes memory corruption. See Rewriting CommonMark Nodes in Perl "right" this time for a working [...] 2019-09-12T23:00Z http://johnbokma.com/blog/2019/09/04/iso-week-and-year-in-perl.html Today I discovered a bug in how the Perl version of tumblelog, the static microblog generator I wrote, calculates the archives; instead of the ISO year I used the actual year, which resulted in subtle errors at the beginning and end of some years while [...] 2019-09-04T23:00Z http://johnbokma.com/blog/2019/08/11/adding-twitter-card-and-facebook-sharing-support-to-tumblelog.html In the afternoon I added a new template variable to tumblelog, both the Perl and the Python version. Thanks to this additional variable, page-url, it's easy to add support for Twitter card and Facebook sharing to a static blog generated with [...] 2019-08-11T23:00Z http://johnbokma.com/blog/2019/06/16/git-permission-issue-with-virtualbox-shared-folders.html Last Friday I ran into an odd issue with git svn clone inside a shared folder of VirtualBox 6.0.8 with Ubuntu 19.04 the guest OS and MacOS Mojave the [...] 2019-06-16T23:00Z http://johnbokma.com/blog/2019/06/08/clean-install-mojave-fusion-drive.html Today I performed a clean install of macOS Mojave 10.14 on the fusion drive of my Mac Mini 2014. Below I have written down my [...] 2019-06-08T23:00Z http://johnbokma.com/blog/2019/05/30/building-goaccess-from-source-ubuntu.html Yesterday I built GoAccess, an open source web log analyzer, from source on Ubuntu 16.04.1 because the version available via the repository was severely outdated. Today I decided to write down my notes as a blog and generate a few reports to illustrate this useful [...] 2019-05-30T23:00Z http://johnbokma.com/blog/2019/05/27/ssh-public-key-authentication.html I recently helped someone out with creating a key pair for SSH public key authentication. Because this might be useful for others I decided to write down my notes [...] 2019-05-27T23:00Z http://johnbokma.com/blog/2019/05/21/finding-duplicate-files-with-jdupes.html For the past years I have used fdupes by Adrian Lopez to find and delete duplicate files on my Linux machines virtual or actual. It's a great program and I love the interactive delete mode. Then I learnt that Jody Bruchon had written a much faster version, called jdupes; in which the j most likely stands [...] 2019-05-21T23:00Z http://johnbokma.com/blog/2019/05/20/twitter-card-and-facebook-sharing.html Some time ago I added a Twitter card to several pages of my blog. A Twitter card is an image with some information underneath displayed by Twitter when you post a tweet. Such a card can be more attractive than a mere link and hence might result in a higher click-through ratio. The image and the information [...] 2019-05-20T23:00Z http://johnbokma.com/blog/2019/05/13/blacklisting-domains-with-postfix.html My experience is that top level domains like .icu, .win, .trade, etc. are a source of spam. Because I don't expect actual email from those domains I decided to blacklist those domains as well as several countries in [...] 2019-05-13T23:00Z http://johnbokma.com/blog/2019/04/19/building-the-latest-version-of-proxychains-ng.html Today I was working with an older version of ProxyChains which has the habit of printing to [...] 2019-04-19T23:00Z http://johnbokma.com/blog/2019/04/12/seo-friendly-titles-for-tumblelog.html One of the big issues with the tumblelog program, both the Perl and Python version, I wrote is that it doesn't use SEO friendly titles. For the main index page and the week overviews it's hard to come up with a title that makes sense other than "everything but the kitchen sink". But for the day pages, [...] 2019-04-12T23:00Z http://johnbokma.com/blog/2019/04/12/additional-font-locks-for-markdown.html Yesterday I have been experimenting with adding new keywords to Markdown mode in Emacs. Because I use Markdown with some of my own rules for my tumblelog Plurrrr I wanted some additional high lighting, font locking in Emacs [...] 2019-04-12T23:00Z http://johnbokma.com/blog/2019/04/08/python-re-sub-gotcha.html Today, I noticed that the following code excerpt in a Markdown file for my tumblelog [...] 2019-04-08T23:00Z http://johnbokma.com/blog/2019/04/07/tumblelog-python.html Friday and Saturday I worked on porting my Perl version of a static tumblelog generator to Python. Even though I hadn't programmed in this language for quite some time I was able to write Python fluently again after a very short [...] 2019-04-07T23:00Z http://johnbokma.com/blog/2019/04/03/a-json-feed-for-tumblelog.html Yesterday I started with adding a JSON feed to the static tumblelog generator I wrote in Perl. I used the JSON Feed Version 1 specification which has sufficient [...] 2019-04-03T23:00Z http://johnbokma.com/blog/2019/04/02/fixing-skipping-ssh-dss-key.html Yesterday I switched the remote for the tumblelog repository to SSH. I used originally, by accident, HTTPS but prefer [...] 2019-04-02T23:00Z http://johnbokma.com/blog/2019/03/30/tumblelog-perl.html This week I wrote a static tumblelog generator in Perl. It creates a microblog very similar to the well-known tumblelog [...] 2019-03-30T23:00Z http://johnbokma.com/blog/2019/03/21/driving-a-perl-script-via-find.html A week ago I wrote a quick hack to parse all the HTML pages containing blog posts of my old blog, find the first h1 element and print the text contained within along with the filename to stdout. Next, I used search and replace in Emacs to turn the filenames into [...] 2019-03-21T23:00Z http://johnbokma.com/blog/2019/03/08/posting-a-tweet-picked-from-a-file-at-random.html Today I finished a small Perl program that I started on yesterday; a program to pick a tweet from a file at random and post it to Twitter. The idea is to post automatically, using cron, 3 or 4 tweets a day to promote my [...] 2019-03-08T23:00Z http://johnbokma.com/blog/2019/03/08/running-a-perl-program-via-cron.html If you want to run the tweetfile.pl Perl program I wrote at regular intervals, say three times a day, you can use [...] 2019-03-08T23:00Z http://johnbokma.com/blog/2019/03/04/proxying-multiple-locations-with-nginx.html Yesterday a customer from Japan contacted me if he could test the Perl application I had written on a test server on the Internet first. Since I had already the application running in a virtual machine on my 2014 Mac mini I decided to create a reverse tunnel and proxy to it from an existing site instead [...] 2019-03-04T23:00Z http://johnbokma.com/blog/2019/02/28/how-to-alias-a-file-in-apache.html In the early evening I wanted to configure the Apache webserver I run on Ubuntu in a virtual machine to host a local version of this website. Because currently my personal website is split in an old part and a new part residing in different directories I had to use the Alias directive to map my new blog [...] 2019-02-28T23:00Z http://johnbokma.com/blog/2019/02/22/how-to-make-python-scripts-work-in-the-gimp.html Today, I suddenly got an insight as to why a Python script I had written was not working in the Gimp running on Ubuntu 18.10: maybe I had to install additional support for Python. And indeed, if you install the GNU Image Manipulation Program via the command line as [...] 2019-02-22T23:00Z http://johnbokma.com/blog/2019/01/05/info-fouseragent-rendered-page.html Today I was working on my homebrew invoice rendering program which uses the Saxon XSLT processor and Apache FOP. The latter program reports for each invoice rendered a log line in the terminal as [...] 2019-01-05T23:00Z http://johnbokma.com/blog/2017/07/07/an-earth-snake-on-the-road.html In the afternoon, when Esme came back from picking up the children she had a small surprise for me: a snake. On the way back from school she and the children had spotted a snake on the road. She had managed to lift the snake using a pencil and put it in a paper bag she was carrying. Most likely she had [...] 2017-07-07T23:00Z http://johnbokma.com/blog/2017/06/29/in-memory-compression-and-decompression-of-json-data.html Today, for a project I am working on I wanted to compress and decompress JSON data in-memory. Yesterday, in the evening, I had already read the documentation of IO::Compress::Gzip, a Perl module I had used before in the past, as a refresher. Based on the examples given in the documentation was quite [...] 2017-06-29T23:00Z http://johnbokma.com/blog/2017/06/26/running-ubuntu-17-04-on-virtualbox-with-shared-folders.html Today I decided to create a new Ubuntu 17.04 virtual machine on my Mac mini. I had already made one a few weeks ago, but not really happy with the disk size I had selected; too large. Nor was I happy with mounting shared folders via rc.local, see Mounting VirtualBox Shared Folders. This time I wanted [...] 2017-06-26T23:00Z http://johnbokma.com/blog/2017/06/20/how-anxiety-got-me-rejected-twice-today.html Today, just after noon I emailed about 60 people if they were interested in hiring me as a Perl programmer. I had attached the PDF version of my up-to-date resume instead of a link for download to save the recipient time. Soon after, sooner than expected, I got my first reply. It was, however, the third [...] 2017-06-20T23:00Z http://johnbokma.com/blog/2017/06/20/virtualbox-shared-folder-cmake-symlink-library-fail.html In the morning I decided to do some work on my Markdown-to-site project, a project that will eventually generate this website. At this early stage the project required me to install the Perl module [...] 2017-06-20T23:00Z http://johnbokma.com/blog/2017/06/15/disappearing-claws-in-the-dark.html In the afternoon, Esme and I left to for the nearyby town of Chavarrillo. We had planned to do another evening hike in the nearby canyon; our fourth one this year. The reason I wanted to go back once more is that on our first hike this year I had found a specimen of Centruroides rileyi. A species I had [...] 2017-06-15T23:00Z http://johnbokma.com/blog/2017/06/08/using-a-plastic-ice-bucket-as-orchid-pot.html Today, on her way back from teaching English, Esme went to Casa Ahued, a shop located near the center of Xalapa. I had asked her to look for a large transparent plastic pot to repot one of my orchids into. Casa Ahued sells a large variety of cheap plastic wares and hence Esme and I often refer to it [...] 2017-06-08T23:00Z http://johnbokma.com/blog/2017/06/06/logitech-m215-works-with-raspberry-pi-2.html Today, I decided to check if the Logitech M215 wireless mouse I had in storage would work with a Raspberry Pi 2 Model B. The latter I had ordered with Amazon nearly 2 years ago and was part of the CanaKit Raspberry Pi 2 Ultimate Starter Kit with WiFi . Until recently it was used for running OpenElec, [...] 2017-06-06T23:00Z http://johnbokma.com/blog/2017/06/04/flashing-linksys-e1500-with-dd-wrt.html Today I flashed a Linksys E1500 router with DD-WRT firmware. The router got originally decommissioned because it had a backdoor in the original firmware and to me it was easier to buy a new but different router and flash it with OpenWrt. So the E1500 ended up in a box until I decided to turn it into [...] 2017-06-04T23:00Z http://johnbokma.com/blog/2017/05/30/adding-color-to-latex-resume.html Today, after I had rewritten parts of my resume, I decided to give changing the color of the section headings a shot. I generate the PDF version of my resume via a Pandoc LaTex template. Adding support for color to the template had been on my todo list for a while and it turned out easier than I [...] 2017-05-30T23:00Z http://johnbokma.com/blog/2017/05/17/installing-latest-pandoc-on-ubuntu.html This tutorial describes how I installed the latest version of Pandoc on Ubuntu 17.04 and installed additional packages in order to convert my resume written in Markdown to a PDF [...] 2017-05-17T23:00Z http://johnbokma.com/blog/2017/04/29/a-juvenile-opossum-in-the-kitchen.html In the evening, while Esme and I were watching a movie, we suddenly both saw something moving from the corner of our eyes. Because it was still quite hot in the house we had left the front door open. And something large had just walked in and was beelining for the kitchen. Just like Milo in the Alex [...] 2017-04-29T23:00Z http://johnbokma.com/blog/2017/04/28/redirecting-a-post-as-get-in-perl.html Today, while testing a Perl implementation of a module to use a web based API, I bumped into the fact that LWP redirects a POST request as another POST request, when enabled. The web based API, though, insisted on a GET [...] 2017-04-28T23:00Z http://johnbokma.com/blog/2017/04/27/perl-base64-hmac-sha256-signatures-padding.html Today, while porting a Python implementation of a web based API to Perl I ran into a minor issue: the Perl module I used to generate a Base64 encoded HMAC SHA256 signature does not pad the Base64 result in such a way that the length of the result is always a multiple of [...] 2017-04-27T23:00Z http://johnbokma.com/blog/2017/04/24/tunneling-an-api-callback-to-dev.html A project I am currently working on uses a web based API for keyword research. Because results are not available right away there are two options: polling for results or providing a callback URL. Of course, the latter is more efficient. So today I looked into setting up a reverse tunnel over SSH from [...] 2017-04-24T23:00Z http://johnbokma.com/blog/2016/11/26/viewing-djvu-documents-on-os-x.html Today I downloaded a DjVu document to my Mac Mini running OS X El Capitan. I was expecting to be able to view such a document on OS X without having to install any 3rd party software. Alas, the document format was not [...] 2016-11-26T23:00Z http://johnbokma.com/blog/2016/10/04/mounting-virtualbox-shared-folders.html Yesterday I experimented a bit with VirtualBox shared folders. I was able to share several directories in my home directory on OS X under my home directory on a Ubuntu 16.04.1 installation running in a virtual machine. Today I wanted to repeat the steps and write everything [...] 2016-10-04T23:00Z http://johnbokma.com/blog/2016/09/21/docker-for-mac-named-volume-speed-penalty.html Based on some test I did today; importing a 10MB gzip compressed MySQL database dump, it seems that using a named volume is over twelve times slower than using bind mount on Docker for Mac version 1.12.1. When a named volume is used the data is stored into a virtual harddisk Docker.qcow2. Besides the [...] 2016-09-21T23:00Z http://johnbokma.com/blog/2016/09/14/padding-numbers-with-zero-in-perl.html Today I saw a piece of Perl code to format a date and time that uses what I consider a clusmy way to do zero padding. I have seen this method or a variation thereof before; it checks if a number is smaller than 10 and if this is the case it converts the number to a string, adding a zero in front of it. [...] 2016-09-14T23:00Z http://johnbokma.com/blog/2016/09/13/getting-started-with-docker-for-mac.html Today I finally was able to make some time to install Docker for Mac. Yesterday, in the evening I had already been rereading the first two chapters of The Docker Book by James Turnbull. This ebook is updated often and hence at 9.99 USD I consider this money well [...] 2016-09-13T23:00Z http://johnbokma.com/blog/2016/09/13/updating-ipad-air-2-to-ios-10.html Despite reported issues with upgrading to iOS 10 I decided to take the plunge today, and make an attempt to upgrade my iPad Air 2 to iOS [...] 2016-09-13T23:00Z http://johnbokma.com/blog/2016/09/09/making-notes-available-via-icloud.html The iOS Notes app is one of the programs I use a lot on my iPad Air 2. Currently, I have 60 notes. Most of these notes are used to store web links, each note a specific topic. I really like how Notes renders links, and how easy it is to add new links from various apps to my [...] 2016-09-09T23:00Z http://johnbokma.com/blog/2016/09/06/migrating-firefox-to-os-x.html Today I migrated some of my Firefox settings from Linux to OS X. I decided to move only the settings I required instead of my entire profile, and install the extensions fresh even though just migrating the profile caused no issue when I migrated [...] 2016-09-06T23:00Z http://johnbokma.com/blog/2016/09/02/migrating-paralles-vm-to-virtualbox.html The 31st of August I removed Parallels Tools from a virtual machine running Ubuntu 15.10 because the grace period of 7 days, so "generously" given by Parallels after I didn't renew my subscription, had ended. Somehow this company considers it a smart move to make their software useless if one no longer [...] 2016-09-02T23:00Z http://johnbokma.com/blog/2016/08/28/fixing-broken-links-in-rss-feed.html Today, when reviewing the HTML site stats report made using GoAccess of this web site's current access log I noticed blog related URLs to the /blog/ part in the URL. [...] 2016-08-28T23:00Z http://johnbokma.com/blog/2016/08/28/blocking-unwelcome-site-traffic.html After having generated an HTML report with GoAccess of this web site's current access log I noticed two IPs that had made a lot of requests to my site; 46.161.9.31 and 46.161.9.32. The top search in Google for the first IP address led to IP Reports for 46.161.9.31. The origin of the IP address is the [...] 2016-08-28T23:00Z http://johnbokma.com/blog/2016/08/28/generating-an-html-report-with-goaccess.html This month I started blogging again after a hiatus of over 4 years. Curious if my site was already getting more traffic, and to which pages, I wanted to make a report of my sites' access [...] 2016-08-28T23:00Z http://johnbokma.com/blog/2016/08/26/migrating-thunderbird-to-os-x.html Because Parallels Desktop has become practically ransomware; pay or you can't access your virtual machines anymore after a grace period of 6 days, I have some migration to do. To be honest, I have been thinking about this for quite some time, leaving Parallels behind. I bought a Mac mini and working [...] 2016-08-26T23:00Z http://johnbokma.com/blog/2016/08/26/when-software-subscriptions-really-suck.html Today I was greeted by Parallels Desktop with a warning telling me that if I was not going to renew my subscription Parallels would stop [...] 2016-08-26T23:00Z http://johnbokma.com/blog/2016/08/23/getting-started-with-mac-ports.html Some time ago, after having read about the advantages and disadvantages between Mac Ports and Homebrew I decided in favor of the former. I can't actually recall why exactly. It probably had also a little to do with my plans of running FreeBSD 11 on a fanless computer I bought ages [...] 2016-08-23T23:00Z http://johnbokma.com/blog/2016/08/23/installing-git-on-os-x.html Today I checked which version of Git was more recent, the Mac version on the official git site (2.9.2) or the version available via Mac Ports (2.9.3). Since the latter won, and also because I want to use Mac Ports for other software anyway, I decided to install Mac Ports [...] 2016-08-23T23:00Z http://johnbokma.com/blog/2016/08/20/verifying-the-weight-of-a-t-rex-skull.html Today I read a post by the Tri-City Herald on Facebook regarding the arrival of a rare Tyrannosaurus rex skull at the Seattle museum. Besides the usual comments of creationists, mostly very confused about basic science, there was one person who considered the weight given a "big fish [...] 2016-08-20T23:00Z http://johnbokma.com/blog/2016/08/10/the-docker-book-updated.html Today I got an email from James Turnbull regarding an update of "The Docker [...] 2016-08-10T23:00Z http://johnbokma.com/blog/2016/08/10/emacsclient-on-ubuntu.html Over the past few days I have been using emacsclient to open files in an already running emacs in daemon (server) mode. Despite having been using Emacs for years I never got around to trying this out for a few days. And I really like it. So today I decided to switch my workflow to using emacsclient the [...] 2016-08-10T23:00Z http://johnbokma.com/blog/2016/08/09/pandoc-resume-latex-template.html Last week, from Wednesday until Friday; and even a little in the weekend, I have been working on an up-to-date version of my resume. The last version available for download hadn't been updated since 2004. Moreover, I was never really happy with it; too many [...] 2016-08-09T23:00Z http://johnbokma.com/blog/2016/08/02/tar-files-in-other-directory.html Today I wanted to send some PDF files on blogging to a friend. I have those files in a "Blogging" directory which I can access using WebDAV with SSL on my iPad. I use this set up to sync PDF books to the GoodReader iOS app, which I can't recommend enough if you want to read PDFs on an [...] 2016-08-02T23:00Z http://johnbokma.com/blog/2016/08/01/adding-a-column-and-foreign-key-mysql.html A database table, part of a project I am currently working on, required an additional column with a foreign key. Because the database has already valuable data I couldn't just drop all tables and start fresh, but had to alter the existing [...] 2016-08-01T23:00Z http://johnbokma.com/blog/2016/08/01/non-fiction-reading-list-rest-of-2016.html Back in April I ordered several books on Amazon, including three non-fiction books for myself. And back in June I ordered several more books on Amazon, including three more non-fiction books for [...] 2016-08-01T23:00Z