Moving to KDE – is it worth it?

I’m Ubuntu enthusiast. However, since Gnome introduction as default in Ubuntu, I’ve been experiencing stability issues. I don’t mind to reboot my laptop from time to time, but my workstation is a different story – often many weeks without reboot.

After many discussions with my friend, I’ve decided to give a try to KDE. I’ve been experimenting with KDE years ago and I found it not straightforward to use. But apparently since version 5 it’s possible to customise KDE to look & feel nearly whatever you like. And I have to admit, I got sucked by it after just a few hours. First of all, it’s very stable, quite lightweight and very practical. It’s also pretty – it doesn’t matter that much for productivity, but it’s nice add-on. I felt in love with drop-down terminal. Setting everything so migration from Gnome was smooth took me a few hours for the first time. But it paid off rather quickly, cause I’m way more productive than before. That’s how my screen looks like more or less.

If you want to try it, I’d recommend trying KDE Neon instead of Kubuntu, as Neon is developed by KDE Community, therefore it’s the purest KDE experience you can get. Below, you can find a list a widgets, applications and customisations which made my life easier (again, big thanks to Maciek for helping with the migration!).

Widgets:

  • (Add widgets)
    • system load viewer [set compact view]
    • Global menu
  • (Add widgets > Get new widgets > Download new plasma widgets)
    • event calendar (replace standard clock & calendar)
  • from github
    • https://github.com/jsalatas/plasma-pstate

Applications (installed through Discover)

  • thermal monitor
  • redshift + redshift control
  • latte
  • dropbox
  • netspeed widget

Terminal

  • yakuake (drop-down terminal activated with F12)
  • workrave
sudo apt install yakuake workrave htop
yakuake &
latte-dock &

Tweaks

I’ll try to keep it up-to-date. Hope someone will find it useful. I did already, while installing Neon on the second and third machine 😉

Copy data from Android phone with broken screen

The screen of the phone broke and you want to retrieve your contacts / files… Quite typical story. While getting your photos / files is quite trivial, plugging your phone to computer and copying necessary files would be enough.
The situation with getting out your contacts (if you happened not to sync them with Google) is slightly more complicated. Here is what I did in the case of Samsung S4 mini with broken screen. Note, the digitizer (touch screen) worked, but the USB debugging was OFF. Also, S4 mini has no video output. If your phone happens to have HDMI or MDL, just get the cable and plug it to your TV / monitor 😉

  1. Enable USB debugging
  2. This is hard part and can be done only manually! But it’s quite complicated with broken screen. You need to repeat 3 steps until you reach what you want: make a screenshot (HOME + POWER button in S4 mini), see what’s on the screen (navigate to you Phone storage > Pictures > Screenshots), do some action and repeat… This is extremely tedious, but proved to work with me.
    In Android 4.4 which my phone had, you need to enter Settings > About, scroll down and press many times (~7 should work) Build Number. This will enable `Developer options` in Settings. You need to enter it and tick `USB Debugging` and press OK (here I needed to rotate the screen, as the right side of my digitizer didn’t work…).
    I recommend clicking `Revoke access` and OK, as my computer couldn’t connect till I pressed it.
    Then unplug the mobile phone and plug it again. New dialog asking for permission to access for your computer will appear on the screen. You should tick `Always allow access` and OK. From now on, the access through ADB is possible. You can check it with:

    # install ADB
    sudo apt-get install android-tools-adb
    
    # connect
    adb devices
    adb shell
    

    Note, if your digitizer is working only partially (my case), it’s usefull to enable autorotation first.

  3. Screencast Android to computer monitor
  4. # install seversquare
    sudo apt-get install qt4-qmake libqt4-dev libqtcore4 libqtgui4
    git clone https://github.com/yangh/sevensquare
    cd sevensquare
    
    # for Ubuntu 16.04 replace 5th line of Makefile with 
    	(cd build && qmake-qt4 -o Makefile ../seven-square.pro)
    
    # compile
    make
    
    # and run
    build/seven-square &
    

    Now, you should see the mobile screen and be able to interact with it your mouse & keyboard. Now exporting contacts should be trivial, right?

I have tried to dump userdata partition, but on original system version there is no root access and getting one would erase the data…

Let me know if there is any simpler solution!

Create Windows USB stick under Ubuntu

Today, I needed to create Windows 10 USB key in order to install it in the laptop. I found it not so straightforward under Ubuntu… But quickly I found a simple solution, WinUSB.

# install WinUSB
sudo add-apt-repository ppa:nilarimogard/webupd8 && sudo apt update && sudo apt install winusb

# without USB formatting
sudo winusb --install Win10.iso /dev/sdd

# with USB formatting - this didn't work for me, due to boot loaded installation fauilure
sudo winusb --format Win10.iso /dev/sdd

Source: webupd8.

Raspberry Pi2 with Ubuntu Sever and Drupal?

I decided to celebrate 25th B-day of Linux by putting the latest Ubuntu 16.04 on my Raspberry Pi 2 and setting up a webserver.
This is how I did it:

  1. First, get Ubuntu armf image and prepare memory card
  2. # get image
    wget http://cdimage.ubuntu.com/ubuntu/releases/16.04/release/ubuntu-16.04-preinstalled-server-armhf+raspi2.img.xz
    
    # make sure your SD card is on sdb ie by df -h
    xzcat ubuntu-16.04-preinstalled-server-armhf+raspi2.img.xz | sudo dd of=/dev/sdb
    
  3. Configure new user & setup Drupal8 webserver
  4. # create new user & change hostname
    sudo adduser USERNAME && sudo usermod -a -G sudo USERNAME
    # edit /etc/hostname and add `127.0.1.1 newHostname` to /etc/hosts
    sudo reboot
    
    # generate locales
    sudo locale-gen en_US.UTF-8
    sudo dpkg-reconfigure locales
    
    # install software
    sudo apt install htop apache2 mysql-server libapache2-mod-php php-mysql php-sqlite3 php-curl php-xml php-gd git sqlite3 emacs-nox
    

My first impressions?
sudo apt is veeery slow. At first, I thought it’s due to old SD card I’ve been using, but it’s also true for newer SD card.
Some packages are missing (ie. git-lfs), but you can get them using some workarounds.

But everything just works!
You can check the mirror of https://ngschool.eu/ running on RPi2 here.
Maybe it’s not speed devil, but it stable and uses almost no energy 🙂

Cheers!

Inspired by Ubuntu’s Insights.

Reducing the size of large git repository

The github repository of #NGSchool website has grown to over 5GB. I wanted to reduce the size & simplify this repository, but this task turned out to quite complicated. Instead, I have decided to leave current repo as is (and probably removed it soon) and start new repo for existing version. I could do that, as I don’t care about version earlier than the one I’m currently using. This is short how-to:

  1. Push all changes and remove .git folder
  2. git push origin master
    rm -rI .git
    
  3. Rename existing repo
  4. Settings > Repository name > RENAME

  5. Start new repository using old repo name
  6. Don’t need to create any files as all already exists.

  7. Init your local repo and add new remote
  8. git init
    git remote add origin git@github.com:USER/REPO
    
  9. Commit changes and push
  10. git add --all . && git commit -m "fresh" && git push origin master
    

Doing so, my new repo size is below 1GB, which is much better compared to 5GB previously.

Convert xls table into abstract book PDF

I had to generate Abstract book for #NGSchool2016 (). I had spreadsheet generated by Google Forms with all necessary information. I could copy-paste all entries and format it later on, but I found LaTeX more robust for the task.
As I had already LaTeX template, the only missing part was conversion of .xls to .tex. Thus I have written simple script, xls2tex.py, that generate .tex file based on table from .xls file.
This script, among many other things, convert utf into LaTeX escape characters.

xls2tex.py depends on xlrd and utf8tolatex (from pylatexenc/latexencode, but this is given as single file)

# install dependencies
sudo apt-get install python-xlrd
# generate tex
xls2tex.py

# generate pdf
make

Output pdf.

Github push fails due to large files

Lately, I have had lots of problems with pushing large files to github. I am maintaining compilation of materials and software deposited by other people, so cannot control the size of files… and this makes push to fail often.

git push
remote: error: GH001: Large files detected. You may want to try Git Large File Storage - https://git-lfs.github.com.
remote: error: Trace: 6f0f7f66995a394598595375954732db
remote: error: See http://git.io/iEPt8g for more information.
remote: error: File chip_seq/reads/sox2_chip.fastq.gz is 109.69 MB; this exceeds GitHub's file size limit of 100.00 MB

To remove large files from commit, execute

git filter-branch -f --index-filter 'git rm --cached --ignore-unmatch chip_seq/reads/sox2_chip.fastq.gz'
git push

To add large files using git-lfs, execute

# tract by git lfs files larger than 50MB, skipping those in .git folder
find . -type f -size +50M ! -iwholename "*.git*" | rev | cut -f1 -d'/' | rev | xargs git lfs track
# 
git add --all . && git commit -m "final" && git push origin

Make sure that your file are smaller than 2GB, otherwise your push will fail again 😉

Then, to before pull in another machine, make sure to install git-lfs

git lfs install
git pull

Stream audio & video from webcam using VLC

Yesterday, I’ve posted about streaming webcam image to www using motion. This solution, although very simple, has many limitations, lack of sound, usage of high bandwidth and low image quality, just to mention a few. In a way, motion stream is just a set of jpeg files.
In order to solve all of these, I have spend quite some time playing with VLC, an open source cross-platform multimedia player, that is able to transcode and stream audio & video.
Streaming can be started from graphical interface, just go to:

Media >> Stream… >> Capture Device, select your devices, Add HTML destination (ie. :8080/webcam.ogg), select Video-Theora + Vorbis (OGG) profile & press Stream.

You stream will be available at: http://localhost:8081/webcam.ogg

But normally, using command line is preferred under Linux:

vlc v4l2:// :input-slave=alsa:// :v4l2-standard=1 :v4l2-dev=/dev/video0 :v4l2-width=1280 :v4l2-height=720 :sout="#transcode{vcodec=theo,vb=2000,acodec=vorb,ab=128,channels=2,samplerate=44100}:http{dst=:8081/webcam.ogg}" -I dummy

Initially, I had problem with streaming sound along with video. Adding, `:input-slave=alsa:// :v4l2-standard=1` solved this. You can try another values for `:v4l2-standard` ie. 0, 1 or 2, depending which microphone you want to use.

Above command will stream HD video (1280×720) in .ogg format (natively suported by most browsers) @ ~2Mbps (2000kbps). If you have slower connection, you can change `vb=2000` to `vb=1000` (~1Mbps) and play with lower resolutions. You can check available resolutions of your camera by:

lsusb -v | egrep -B10 'Width|Height'

This stream, however, is available to everyone. To limit it only to localhost, you can use iptables:

sudo iptables -A INPUT -p tcp -s localhost --dport 8081 -j ACCEPT && sudo iptables -A INPUT -p tcp --dport 8081 -j DROP && vlc v4l2:// :input-slave=alsa:// :v4l2-standard=1 :v4l2-dev=/dev/video0 :v4l2-width=1280 :v4l2-height=720 :sout="#transcode{vcodec=theo,vb=2000,acodec=vorb,ab=128,channels=2,samplerate=44100}:http{dst=:8081/webcam.ogg}" -I dummy

Now, you can create apache2 proxy, similarly to previous post:

# install apache2-utils
sudo apt install apache2-utils
 
# setup new user & passwd
sudo htpasswd -c /etc/apache2/.htpasswd webcam

# configure apache2 - add to your VirtualHost config
    # webcam
    <Location "/webcam.ogg">
        ProxyPass http://localhost:8081/webcam.ogg
        ProxyPassReverse http://localhost:8081/webcam.ogg
        # htpasswd
        AuthType Basic
        AuthName "Restricted Content"
        AuthUserFile /etc/apache2/.htpasswd
        Require valid-user
    </Location>

Streaming image from webcam through www

Willing to stream image from your webcam through Internet? Nothing easier with Ubuntu!

# install
sudo apt-get install motion

# create config file
mkdir ~/.motion && gedit ~/.motion/motion.conf

# define the port and motion settings
webcam_port 8081
webcam_localhost on
# increase maxrate & quality
webcam_maxrate 30
webcam_quality 90
# slow down the stream to 1 frame per second if no motion
webcam_motion on

# run motion
motion

You can find the stream at http://localhost:8081/.

If you wish to stream it publicly, I recommend at least basic HTTP based authentication.

# install apache2-utils
sudo apt install apache2-utils

# setup new user & passwd
sudo htpasswd -c /etc/apache2/.htpasswd webcam

# configure apache2 - add to your VirtualHost config
    # webcam
    <Location "/cam">
        # proxy
        ProxyPass http://localhost:8081/
        ProxyPassReverse http://localhost:8081/        
        # htpasswd
        AuthType Basic
        AuthName "Restricted Content"
        AuthUserFile /etc/apache2/.htpasswd
        Require valid-user
    </Location>

Now, image from your webcam will be accessible at http://YOURDOMAIN.COM/cam

Finally, you can configure motion to run only when you are away.

Inspired by gist.