Don’t use Java in a nuclear facility

From the license of Java, Section 3:

“… You acknowledge that Licensed Software is not designed or intended for use in the design, construction, operation or maintenance of any nuclear facility. …”

_{Found here.}

Update (20130318)
It seems the original text has changed. The new version says: “You agree that neither the Software nor any direct product thereof will be exported, directly, or indirectly, in violation of these laws, or will be used for any purpose prohibited by these laws including, without limitation, nuclear, chemical, or biological weapons proliferation.”

Hmm, I preferred the old one :(

A little help for hyphenating words in LaTeX

Problem
When working with LaTeX, sometimes I’m not sure if a word is correctly hyphenated by LaTeX so I’d like to verify that. As I’m not a native English speaker, it’d be nice to hear the correct pronunciation too.

Solution
I made a little script that addresses the two problems (available here). It’s part of my jabbapylib library. The script relies on dictionary.com.

apt-get: “the following packages have been kept back”

Problem

You install something with apt-get and it keeps telling you that some “packages have been kept back”. Great! What to do with that?

Solution

After looking at this warning for years, today I got fed up and looked after it on Google. I found the solution here. If you have a package called X kept back, then try to install it with “sudo apt-get install X“. That’s all.

Some beautiful conky setups

http://www.linuxandlife.com/2011/09/beautiful-conky-linux.html

Windows 7 stops booting in Virtualbox

Problem

I installed Windows 7 in Virtualbox and it worked fine until I installed all the updates… After that the boot process stopped at the splash screen and nothing happened. Neither restart nor boot in safe mode helped.

Solution

Close Virtualbox completely. Restart it and go to the Settings of Windows 7. Here change some parameters, e.g. the number of processors and the amount of memory reserved for the system. After this Windows 7 booted up normally. I could even restore the settings without corrupting the booting process.

Firefox 7 beta

Yesterday I tried Firefox 7 beta. After one day of usage I can say that it works well. I could even install my favorite add-ons.

With FF6 I had some problems: from while to while it blocked for several seconds, the CPU was running on 100%, and then everything came back to normal. I tried to clean my ~/.mozilla folder but the problem remained. I think I could have solved it by removing ~/.mozilla completely but then I said to myself: “let’s try FF7 then”. So I closed FF6, renamed ~/.mozilla to ~/.mozilla6.bak and started FF7 that created a new ~/.mozilla folder. No more blockings :)

I’ve never liked the new tab button but there is an easy way to get rid of it. Right click next to it, from the popup choose Customize…, and then drag and drop the new tab button (probably it’ll be on the right side) to the list. Done. This tip is from here.

Powerpoint is dead (HTML5 presentations with landslide)

Powerpoint is dead. Well, not yet, but for simple presentations you can use the following tool perfectly. This entry is based on Francisco Souza’s excellent post entitled “Creating HTML 5 slide presentations using landslide“. Here I make a short summary.

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Landslide is a Python tool for converting marked-up texts to HTML5 slide presentations. The input text can be written in Markdown, reStructuredText, or Textile. A sample slideshow presenting landslide itself is here.

Sample input: 2.md (taken from the landslide project)
Sample output: presentation.html

Installation

sudo pip install landslide

Usage

landslide text.md

If you want to share it on the Internet: “landslide -cr text.md“.

Help: “landslide --help“.

To learn about the customization of the theme, refer to Francisco’s post.

Convert to PDF

landslide file.md -d out.pdf

For this you need Prince XML, which is free for non-commercial use. Unfortunately the output is black and white with additional blank pages for notes. If you know how to have colored PDFs without the extra pages, let me know.

It’d be interesting to replace Prince XML with wkhtmltopdf. I made some tests but the output was not nice. I think it could be tweaked though.

Related stuff

Pandoc is a universal document converter.

“If you need to convert files from one markup format into another, pandoc is your swiss-army knife. Need to generate a man page from a markdown file? No problem. LaTeX to Docbook? Sure. HTML to MediaWiki? Yes, that too. Pandoc can read markdown and (subsets of) reStructuredText, textile, HTML, and LaTeX, and it can write plain text, markdown, reStructuredText, HTML, LaTeX, ConTeXt, PDF, RTF, DocBook XML, OpenDocument XML, ODT, GNU Texinfo, MediaWiki markup, textile, groff man pages, Emacs org-mode, EPUB ebooks, and S5 and Slidy HTML slide shows. PDF output (via LaTeX) is also supported with the included markdown2pdf wrapper script.“

Zombie.js, PhantomJS

This is not a real post, just a reminder for me. I should look at these projects in detail in the future.

“Zombie.js is a fast, headless full-stack testing using Node.js. Zombie.js is a lightweight framework for testing client-side JavaScript code in a simulated environment. No browser required. Here is a Python driver for it called python-zombie.”

“PhantomJS is a headless WebKit with JavaScript API. It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas, and SVG. PhantomJS is an optimal solution for headless testing of web-based applications, site scraping, pages capture, SVG renderer, PDF converter and many other use cases.“

Node.js

I’ve heard a lot about node.js recently so I looked after it a bit. At the homepage of the project you can find a one-hour long video presentation of the project.

Node.js is a set of libraries on top of Google’s V8 Javascript engine, which is used in Chrome. V8 is a very high performance virtual machine. Node.js uses the greatness of V8 to do networking things. The focus is on doing networking correctly.

Examples

Hello World:

setTimeout(function() {
    console.log('world');
}, 2000)
console.log('hello');

It registers that the first function must be executed in 2 sec. and it goes on. It prints ‘hello’, then ‘world’ 2 sec. later. One very important thing: in node.js there is no blocking (like sleep()). The program exits when there is nothing else left to do.

Simple web server:

var http = require('http');

var s = http.createServer(function(req, res) {
    res.writeHead(200, {'content-type' : 'text/plain'});
    res.write("hello\n");

    setTimeout(function() {
        res.write("world\n");
        res.end();
    }, 2000)
});

s.listen(8000);

All these examples are from the introductory video. In the video there is also a TCP server. He also shows a simple chat server via TCP.

Installation
Under Ubuntu I already had a “node” command. According to “man node” it was something different so I removed it (sudo apt-get remove node).

Download the source from the HQ, extract it, then configure, make, sudo make install.

Start it with the command “node” and you get a prompt. Execute a script with “node file.js”.

Further reading

• What is node.js? @ SO
• npm, a package manager for node
• What is Node.js?
• Node.js is genuinely exciting
• Understanding node.js
• Learning Server-Side JavaScript with Node.js
• Node.js Step by Step: Introduction
• Node.js is Cancer (Ted Dziuba doesn’t like Node.js)

QR code (square barcode) maker / decoder

Nowadays I see everywhere these stupid square barcodes. Today I looked after what the heck these are.

• Wikipedia article on QR codes. It turns out that it’s Japanese.
• online generator
• online decoder
• some more info on barcode contents
• some Python libraries (didn’t try them)
• Google API for QR codes (example)

Update (20130805): here a QR generator, written in pure Python.