Blog posts about Hacks

Our comments on this topics (ordered by publication date, newest first):

• 52. Big MediaWiki Upgrade (1.21 to 1.43) on 09:42, 6 July 2025

In June‒July (2025), I upgraded Mediawiki from 1.21.5, which is a 2013 version, to 1.43.2, the most recent one at the time of writing (13 years later).

• 51. Emacs locale and Luz's birth date according to Grok on 17:29, 20 February 2025

I had the problem that emacs was using French dates rather than POSIX ones from Shell interactions. This is fixed by adding in .emacs:

(setenv "LC_ALL" "en_US.UTF-8")  ; Overrides all locale settings, including LC_TIME

(could be POSIX there, but what I really want is English dates). One nice feature of this solution is that it's the first time I use Grok (newly-released v°3) to help me solve something!

• 50. Emacs Proofing LaTeX on 12:11, 18 May 2024

I often need to clean out the proofing notes one makes for editors and co-authors in $\mathrm{\LaTeX}$ prose:


• 49. Debugging sopi on 15:37, 5 January 2024

sopi works great except when it doesn't, in which case he just vomits an error message like this:

• 48. Moving numbered files to add one entry on 09:57, 26 September 2023

Say you have files like this:

lecture1.tex
lecture2.tex
lecture3.tex
...
lecture13.tex
lecture24.tex

and need to add a new lecture5!

• 47. doi2bib or parsing doi into bibTeX entries on 16:53, 30 July 2023

From about 2003, when I started to compile scientific references, till now, I have been entering references in my sci.bib bibTeX file by hand! That included 3549 entries according to bibtex-count-entries. This stops today.

• 46. bib2wiki or parsing bibTeX into mediawiki templates on 19:44, 16 July 2023

In a previous post, I was discussing a prospective bib2wiki script to automatize the transcription of my bibTeX database to laussy.org (this website). This was over 10 years ago, so I forgot what I did back then. I had to do it again.

• 45. Overlapping subtitles in kdenlive on 15:19, 10 July 2023

kdenlive uses a 25th of a second accuracy for the millisecond timestamp $t$, which thus becomes converted to the nearest integer $\lfloor{t/40}\rceil$ (there are forty fractions of 1/25s in a second). So if you have, say:

00:00:02,764 --> 00:00:03,705
So now...

• 44. Timestamps in srt files with Mathematica on 22:18, 9 July 2023

This describes a hack to manually find the overlapping subtitles in a srt file (and do other more interesting things).

• 43. Extracting citation counts from a Google Scholar page on 12:59, 25 June 2023

Say you want to extract the citation counts from someone's Google Scholar page (here from Jeremy Baumberg):


• 42. Merging Columbus CSV files on 00:32, 6 January 2023

To merge various tracks from the Columbus P-10 device so as to assemble a global picture of your whereabouts, one can follow the steps below.

• 41. CSV to GPX for Columbus P-10 Pro on 23:13, 5 January 2023

However great GPSBabel can be, it still fails to be conversant with the great Columbus GPS logger. This is how we convert its CSV file to GPX.

• 40. Overlay images with Imagemagick on 11:36, 13 August 2022

I should be on Holiday! But I'm trying to finalize this animation for my perspective for Quantum:


• 39. mp3 files in mediawiki without flash on 18:38, 21 March 2021

Flash is no longer supported, maybe the worst thing to happen in 2021 (and there's a pandemic going on). Among some of the best things to go, the fantastic lightweight, efficient and elegant dewplayer to play mp3, which served us so well all this time! (the site says that "Dewplayer n'est plus, mais renaîtra, un jour. «When it's done»). You'd think mediawiki would offer tons of replacement. Strangely, it turns out to be quite difficult to find how to bring mp3 to your wiki! (see what's available). HTML5 is the solution.

• 38. Starting a counter in mediawiki without extension on 10:10, 25 January 2021

Say you want to count like this in mediawiki (not starting at 1):

1. Three
   Four
   Five

The internet tells you it's not possible natively and that you need an extension. Here's an ugly hack to do it anyway! (keeping the # rather than going full HTML).

• 37. Lastres de Mujer animation on 10:33, 18 January 2021

Elena and Julia made a video-clip for Lastres de Mujer, one of Elena's songs (you can see it here). It consists of stop-motion animation of some of Julia's drawings that she arranges in a book. We shot pictures in rafales that we turned up into a movie following these simple steps.

• 36. Stitching mp4 in linux on 09:17, 26 November 2020

Rendering a video is extremely lengthy. If you want to alter a little part of it, you certainly do not want to render the whole thing again. Here's what you can do instead.

• 35. Vals del vampiro animation on 15:38, 9 June 2019

Carlos Sánchez, who has all the talents, composed a song (El Vals del vampiro), for which Elena, in a sequence of events that I did not follow in details, came to compose the lyrics. They decided to make a stop-motion animation to release the piece on YouTube (you can see the result here). At this point, I got involved for the minor technical aspects of assembling the artwork (also from Elena) into the said animation. These are the steps I followed to do so, which I store here mainly for my own recollection.

• 34. Forcing et al. for all BibTeX entries with more than one author on 16:05, 18 March 2018

If you're tight in space (e.g., for a conference abstract) and want all entries to read F. Author et al., BibTeX doesn't usually help you much (biblatex would allow that but the more common natbib doesn't). The easiest fix is to hack the .bst file!

• 33. Timelapse of a drawing on 16:24, 17 March 2018

Elena took various pictures of her drawing Maternidad and wanted to do a timelapse. This lists the steps to do so.

• 32. Supplementary TeX material on arXiv on 13:05, 15 January 2018

Papers increasingly come with a supplementary material. This is in principle good as providing all the gory details, except that often this is where the authors flush out what didn't fit in the allotted space of the main text, so supplementary of PRL, for instances, are particularly tough (as often required-reading)

When you upload your prose to arXiv, you typically want the supplementary to be there as well. That's not easy to do.

• 31. Common.js on mediawiki on 13:26, 12 January 2018

Each mediawiki web has a MediaWiki:Common.js page (see, e.g., that of Wikipedia) that runs java script on each page. That's a powerful tool (apparently to be deprecated at some point). Installation should be straightforward but for some reason, can sometimes be frustratingly painful, so I give a particular example that should work on its own.

• 30. Removing trailing spaces for makeindex on 20:30, 24 March 2017

Makeindex, $\mathrm{\LaTeX}$'s historical index-building engine, is irritatingly buggy. One recurrent problem that plagues the output from careless index makers is that of duplicated entries:



A sore to the eye!

• 29. Making space in gmail on 09:04, 21 February 2016

We all eventually get there:


• 28. Referencing figures by a label in mediawiki on 13:10, 24 January 2016

If you want to refer to images in Mediawiki the way you would in a $\mathrm{\LaTeX}$ document, you can use this cheap trick of mine...

• 27. KDE default profile on 14:16, 14 January 2016

It's a pain that konqueror opens two panels by default in 'filemanagement' mode. I always have to close one by hand.

• 26. Emacs regexp for our compound decay rates notation on 00:36, 13 January 2016

We find that algebraic sums of decay rates are fairly common, which make a notation such as $\gamma_{\widetilde{ij}}=i \gamma_a + j\gamma_\sigma$ useful (e.g., $\gamma_{\widetilde{31}}=3\gamma_a+\gamma_\sigma$). This is, however, a bit of a pain to typeset:

(e.g., $\gamma_{\widetilde{31}}=3\gamma_a+\gamma_\sigma$)

In emacs, this regexp substitution allows to transliterate \gamma_{31} into the widetilde form:

Replace regexp (default _{\([0-9][0-9]\)} -> _{\\widetilde{\1}}): 

• 25. Snowing in the browser on 20:01, 13 December 2014

For Christmas, it's nice to feature a goody on one's website to participate to the overall merrier atmosphere. A favorite and immemorial web touch is the snow fall. It used to be popular on UNIX boxes as well though it apparently isn't so standard nowadays. As for the good old web, we like to use Scott Schiller's snowstorm, bringing snow to the web since 2003.

• 24. 21844 files on 13:13, 7 December 2014

If you look at what computers can do in terms of storing data, you feel sort of safe.

It's $2^{32}-1$ files (that makes 4 294 967 295) for NTFS, only 4 194 304 for FAT32 and a minuscule 65 536 for FAT16 which is however obsolete, while exFAT reads "Nearly Unlimited" [1].

• 23. Changing file extensions in multiple LaTeX files on 17:58, 19 November 2014

That's a pretty concrete problem: I have multiple .tex file which include .eps extensions. I have converted all the postscript (old fashioned) stuff into brand new converted pdf, now calling figure.eps by figure.eps.convto.pdf.

This piece of code says the $\mathrm{\TeX}$ files about that daring move:

perl -pi -w -e 's/\\includegraphics(\S+)pics\/(\S+)\}/\\includegraphics$1fig\/$2\.convto\.pdf\}/g;' *.tex

update on 09:38, 20 November 2014 (EST)[edit]

Now pdflatex doesn't like the extension .eps.convto.pdf (which in my mind was to mean "eps converted to pdf"). So I have to to keep only .pdf:

perl -pi -w -e 's/\\includegraphics(\S+)pics\/(\S+)\.e?ps\}/\\includegraphics$1fig\/$2\.pdf\}/g;' *.tex

(doing this for both extensions .eps and .ps by hand) and use the following bash conversion to replace the extension:

convert "$1" ""${1%%.eps}".pdf"

(here again, both for .eps and .ps). The latter is in a shell file called convertme which I call with:

find fig/ -type f -name *.eps -exec ./convertme {} \;

(here again, both for .eps and .ps by hand)

Note that this wasn't a problem before, where I had .ppm.eps or .png.eps files (which I had to convert in similar ways as above, of course), or even more legitimate UNIX filenames:

! LaTeX Error: Unknown graphics extension: .2.pdf.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.420 ...raphics[height=7cm]{fig/2/Figure2.2.pdf}}

• 22. Inflationary bubbles on 21:47, 21 October 2014

This is the title I gave to this "kinetic digital sculpture" of mine, filed to the Wolfram Tweet-a-Program program:

• 21. Walter Zorn's tooltips v°0.2 on 23:38, 1 May 2014

I have upgraded my extension wz (named after Walter Zorn) to support more features of this great library that provides tooltips.

• 20. Wikilog titles and links on 22:40, 26 April 2014

The Mediawiki Wikilog extension needs a hack to display title properly on our site.

• 19. From maps to multimaps on 19:50, 2 February 2014

I am migrating from Evan Miller's extension of Google Maps, which is now archived (obsolete) to Pavel Astakhov's version, MultiMaps.

• 18. Mediawiki 1.22.1, lua, Scribunto and templates from Wikipedia on 02:02, 20 January 2014

I am upgrading laussywiki to MediaWiki 1.22.1, mainly to support the new citation templates from wikipedia. They are great and I want a better/more thorough and more consistent quotation system.

• 17. Multipage extension for Inkscape on 08:51, 3 September 2013

Inkscape has a multipage extension: http://sourceforge.net/projects/inkscape-pages. Thanks to its authors: Cosmin Popescu!

• 16. Turning Mathematica lists into hashes on 16:29, 13 November 2012

Here is a short hack to turn Mathematica lists into hash tables.

• 15. Defining macros for Mathjax extension on 15:28, 7 June 2012

\(\newcommand{\pt}{\partial_t}\)With MathJax, you can use \newcommand in enclosed $...$ characters to define a macro in any given page (e.g., \newcommand{\pt}{\partial_t} turns $\pt$ into $\pt$). If you want a popular macro to be defined once and for all, without having to include the definition each time, you have to declare it in a Config.js file.

• 14. Positioning the frame of extension Anysite on 11:02, 25 April 2012

This is a trivial patch of MediaWiki Extension:Anysite to shift x-wise the included frame.

• 13. A simple way to quote from bibTeX in MediaWiki on 10:59, 22 April 2012

I would like to quote references in MediaWiki from a $\mathrm{B{\scriptstyle{IB}}\TeX}$ (.bib) file.

The key indexing scheme I use is:

name-of-first-author⇿two-last-digits-of-year-of-publication⇿$\alpha$

• 12. The nightmare of using a mac on 08:55, 18 April 2012

I tried to install an open source software (kdenlive) on a Mac. For this, I had to install macports. For this, I had to install Xcode. For this, I had to register as a Mac OS developer

• 11. Convert QuickTime .mov file to mpeg on 16:21, 31 March 2012

Movies downloaded from a mac bearing the .mov extension may fail to reproduce the video on other platforms (linux, windows, etc.), although the sound would still be played correctly. Most linux players will content to play the audio on a black screen. Xine complains about an unknown 'm2v1' codec. That's this hint which brought me to Carlos Aranda's blog

• 10. Stripping extension from files on 20:13, 21 March 2012

The following command allows a variety of useful operations on files based on stripping their extension:

• 9. Commenting on blog posts on 06:55, 4 March 2012

I hadn't really realized that the possibility for readers to comment on our blog was in fact disabled. Now, this should be remedied. Please say hello!

• 8. Mediawiki Extension News on 17:04, 3 March 2012

I have installed Duesentrieb's Mediawiki Extension:News to keep an up-to-date record of what is new on our website.

• 7. Rescuing files: the last of them on 11:57, 30 December 2011

A friend encountered a silly bug which wiped an entire folder of data (which bug?).

• 6. Remove portrait images on 17:39, 21 December 2011

This little script removes images which appear to be in the portrait format (tweak it for your own needs).

• 5. Installing xv on ubuntu on 10:22, 24 June 2011

The following (originally from someone Kurt [1]) works like a charm:

• 4. We have mouse rollover! on 20:55, 13 June 2011

One of our most cherished goodies in our original website was the mouse rollover, or tooltip. Something like that (roll over!)...

We had to surrender this option when we turned to MediaWiki, since there was no good support for it and, until a few minutes ago, nothing close enough to what we wanted.

Now the situation has changed.

• 3. Removing recursively special and accented characters in filenames on 19:52, 5 June 2011

Don't use non-ASCII characters in filenames.

• 2. LogGrid on 19:34, 11 March 2011

I put here a Mathematica module to generate a logarithmic grid of points between given lower and upper bounds.

• 1. Restoring corrupted Mathematica notebook on 12:01, 3 February 2011

When you have a corrupted Mathematica notebook, which happens more often than not, you can use the wonderful Corruption.m package from Lou D'Andria.