Home - The Movie

"In 200.000 years on Earth, humanity has upset the balance of the planet, estabilished by nearly four billion years of evolution. The price to pay is high, but it's too late to be a pessimist: humanity has barely ten years to reverse the trend, become aware of the full extent of its spoliation of the Earth's riches and change its patterns of consumption.

By bringing us unique footage from over fifty countries, all seen from the air, by sharing with us his wonder and his concern, with this film Yann Arthus-Bertrand lays a foundation stone for the edifice that, together, we must rebuild."

The movie features beautiful cinematography. If for no other reason, then watch it just because it's a masterpiece in showing off the beauties of Earth. Smile

How to add page numbers to the footer of a PDF

You'll need the ghostscript and pdftk packages installed for the following to work.

How to download Chrome and Edge extensions in CRX v3 format

This post is probably going to become outdated pretty fast, so don't be surprised if a few months (or a year) after I wrote this, the method won't work.

For Chrome:
curl -v -o t.crx -L \

For Edge (the Chromium based one):
curl -v -o t.crx -L \

In both cases you've to specify the extension ID in the "extensionID" variable. And of course you can adjust the other URI parameters if you want to.

500 méter

Az alábbi térképen címre kereshetsz vagy kattintással jelölhetsz meg egy pontot, ami köré egy 500 méter sugarú kört rajzol.
Így könnyebben eldönthetik a kutyagazdák/-sétáltatók, hogy az esti kijárási tilalom alatt meddig távolodhatnak el a lakóhelyüktől.

Kattints a következő linkre, majd a betöltődő oldalon a "Run this fiddle" gombra a a térkép megjelenítéséhez:

Telefonokon érdemes fekvő módban nézni, hogy az "Edit in JSFiddle" gomb ne lógjon rá a címkereső szövegdobozra.

Polipo - an HTTP proxy with SOCKS upstream proxy support

There're still a few tools (eg. npm, the Node Package Manager) that only support HTTP proxies and not SOCKS proxies. There're a couple of tools to "socksify" programs without builtin SOCKS support, but they do not work in all scenarios (eg. statically compiled apps, etc.). As a matter of fact, I tried to use npm like this, but it failed with an error message.

So what do you need to work around the issue? An HTTP proxy that can forward the incoming requests over a SOCKS proxy. Polipo can do that for you. Smile

Nautilus Actions became FileManager-Actions

I started using Nautilus Actions approximately 9 years ago and loved the level of (file manager) customization that it allowed without compiling anything, merely by writing shell scripts. Meanwhile the project morphed into Gnome's FileManager-Actions and supports other file managers as well.

Unfortunately it's not included in the official Ubuntu 18.04 repositories, but of course there're workarounds: it's available from a PPA or you can compile it yourself.

I chose the latter and here're the simple commands to do it:
# install build dependencies
sudo apt-get install build-essential checkinstall dblatex gnome-doc-utils gtk-doc-tools intltool libgconf2-dev libgtop2-dev libnautilus-extension-dev libxml2-dev rarian-compat uuid-dev
# download the source
wget "https://download.gnome.org/sources/filemanager-actions/3.4/filemanager-actions-3.4.tar.xz"
# extract
tar -xf filemanager-actions-3.4.tar.xz
# configure the project
cd filemanager-actions-3.4
./configure --with-nautilus --disable-scrollkeeper
# compile
make -j5
# build a DEB package
checkinstall -y -D --pkgname filemanager-actions-nautilus --requires nautilus make install-strip

This builds a Debian package that you can save for later (in case you've to reinstall it or install it on another computer, etc.).

P.S.: You can remove the build dependencies if you've no use for them anymore.
P.S.2: I've attached my build, you're free to use it.

How to generate a password from a number of randomly chosen words on linux

In the following example "/usr/share/dict/words" is a word list and "-n 4" specifies that 4 words are needed:
egrep "^[a-pr-xA-PR-X]{3,}\$" /usr/share/dict/words | egrep -v "[sS]\$" | tr "A-Z" "a-z" | sort | uniq | shuf -n 4 | sed -rn "s/^(.)(.*)/\\U\\1\\L\\2/;H;\${x;s/\\n/./g;s/^.(.*)/\\1/;p}"

How to use the VPN of a Windows virtual machine on the Ubuntu host via VirtualBox

Let's assume that you cannot make a VPN connection work on your Ubuntu host OS, but you can do it in a Windows guest VM. However you'd like to keep working on your host OS. If you've an SSH server on the other side of the VPN tunnel, then you're lucky, because setting up two port-forwardings is all you need.

How to copy a file from a specified offset efficiently

The answer is simple if you know "dd" well. I didn't (know about the skip_bytes and count_bytes iflag options).

Captive portal detection vs. automatic WiFi connection on Android (Lollipop and later)

Since Lollipop (5.1+) you might not be able to connect (or reconnect) to all authenticated (aka. password protected) WiFi networks. The culprit is called "captive portal detection". This feature is intended to help you use public (hotels, airports, etc.) WiFi access points by automatically detecting, when a router redirects all traffic to it's own so called "captive portal", where you can register your device for internet access.

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