2017. november 27.

Share clipboard and drag&drop between VirtualBox host and guest

  1. install VirtualBox guest additions
  2. open Machine > Settings... (Host+S key)
    1. open General > Advanced tab
    2. set Shared Clipboard and Drag'n'Drop to bidirectional

2017. augusztus 5.

How to completely remove Plex Media Server?

Source: https://support.plex.tv/hc/en-us/articles/201941078-Uninstall-Plex-Media-Server

  1. Shut down Plex Media Server
    service plexmediaserver stop
  2. Remove the installed package
    dpkg -r plexmediaserver
  3. Remove the library directory of plex
    rm -R /var/lib/plexmediaserver/Library/Application Support/Plex Media Server/
But then, when I wanted to reinstall it, I ran into some errors, and the solution was to make sure that the /var/lib/plexmediaserver folder exists and the plex:plex user/group has owner access to it:
sudo mkdir /var/lib/plexmediaserver
sudo addgroup plex
sudo adduser plex plex
sudo chown plex:plex /var/lib/plexmediaserver

2017. június 22.

Scanimage produces unreadable lineart image with default settings

Compared to Ubuntu 12.04 and the default settings for Canon LiDE 210 flatbed scanner changed in Ubuntu 16.04.

The default result of a Lineart scan was unacceptable (unreadable).
It turned out, that --resolution was 75, and --disable-dynamic-lineart was no.
Setting options '--disable-dynamic-lineart=yes --resolution 300' for '--mode Lineart' solved the problem.

2017. június 16.

Finding the rightful heir to HP Compaq TC-4400 tablet PC

Finding an affordable business class tablet PC with pen support is not easy nowadays.

Here are some sites that might help with finding something with pen support:

2017. június 11.

Migrating from Ubuntu 12.04 LTS to 16.04 LTS on HP Compaq TC4400 Tablet PC

Setting up Xenial is very similar to setting up Trusty.

First of all, I install synaptic and gdebi, because I don't like the Ubuntu Store thingy:
  • sudo apt-get install synaptic gdebi
Then get back the Gnome Classic look:
  • sudo apt-get install gnome-session-flashback
  • log out to change the window manager by clicking on the icon next to your user name then login again.
Then set up gnome-session-flashback with Compiz
  • Add something to the panel: Alt+Super + Right click
  • Set number of workspaces
    • sudo apt-get install compizconfig-settings-manager
    • in Compiz Config Settings Manager navigate to General / General Options / Desktop Size set the size you want.
  • Change date-time format on panel
    • sudo apt-get install dconf-editor
    • in Dconf Editor navigate to com > canonical > indicator > datetime
      • Set "time-format" to "custom"
      • Set "custom-time-format" to the format you want, i.e. %Y-%m-%d %H:%M:%S
      • Make sure that "show-clock" is check-marked. 
  • Change the Indicator App on the panel to show less
    • Gnome Session Flashback installs indicator-applet-complete, but there are more then one indicator applet that can be downloaded with synaptic. The difference between them is this:
      • indicator-applet-complete is: messaging applications, power settings, bluetooth settings, network settings, sound settings, date and time settings, user accounts, session management
      • indicator-applet is: messaging applications, power settings, bluetooth settings, network settings, sound settings
      • indicator-applet-session is: user accounts, session management
      • indicator-applet-appmenu is: your active application's menu header
    • Other settings can be changed in the Dconf Editor under com > canonical > indicator. (i.e. turn off the language icon)
  • Turn off effects:
    • in Compiz Config Settings Manager navigate to Effects and turn off Animations
  • Set Nautilus (Files) default view to List
  • Make .sh files run on double click

Creating searchable PDFs on Ubuntu 3rd try

Following up on the second try:

My requirements:

  • image layer over text layer
  • good character encoding for Hungarian ű and ő chars
  • good placement of words and lines
  • fair enough good recognition
  • handling more column layout


Set up Tesseract:
  • sudo apt-get install tesseract-ocr
  • from https://github.com/tesseract-ocr/tessdata download the language data you need and put it in tessdata directory (/usr/share/tesseract-ocr/tessdata). E.g. for Hungarian:
    cd /usr/share/tesseract-ocr/tessdata
    sudo wget https://github.com/tesseract-ocr/tessdata/raw/master/hun.traineddata
  • add environmental variable TESSDATA_PREFIX to the directory containing the tessdata directory if you get the error that the language data cannot be found.

Tesseract supported input image formats:
...are the ones supported by Leptonica:

Tesseract searchable pdf output
Example usage with specified language (-l):
tesseract  input.png outbase -l hun pdf

  • image layer over text layer - YES
  • good character encoding for Hungarian ű and ő chars - YES
  • good placement of words and lines - YES 
  • fair enough good recognition - YES: it depends a lot on input quality.
  • handling more column layout - SO-SO: sometimes works (i.e. half page is OK, other half is single column)

This is good enough for me now, so I'm not investigating further.

Set nautilus default view to list

I have no idea how to open this 'Edit > Preferences' window in the gnome flashback, but the dconf editor version worked for me:

  1. Open dconf Editor
  2. Navigate to org.gnome.nautilus.preferences
    1. Set the 'default-folder-viewer' to 'list_view'
  3. Optionally: Navigate to org.gnome.nautilus.list-view
    1. Set the 'default-zoom-level' to 'smaller'
    2. Set the 'use-tree-view' to true

2017. május 28.

Ubuntu Firewall

UFW (Uncomplicated Firewall) comes with Ubuntu preinstalled, but it is disabled by default:
sudo ufw enable

Then you'll have to allow specific ports for some applications.
For example, to allow the default port of Transmission Bittorrent Client:
sudo ufw allow 51413

Another way to allow ports for an application is to create an application profile and allow that profile.
For example to allow Plex Media Server:
  1. Edit (create) the app profile:
    sudo gedit /etc/ufw/applications.d/PlexMediaServer
  2. Paste the following in it:
    title=Plex Media Server
    description=This opens up PlexMediaServer for http (32400), upnp, and autodiscovery.
  3. Allow the profile:
    ufw allow PlexMediaServer
Refer to Ubuntu Wiki and Ubuntu Help for more information about UFW.
The solution for Plex Media Server profile was originally posted on Plex Forum.

Some other useful commands:
List all rules (with reference number):
sudo ufw status numbered
Then the reference numbers can be used to delete a rule:
sudo ufw delete 1
The other way to delete a rule would be like this (for an allow rule):
sudo ufw delete allow 51413

2017. április 6.

How to make .sh files run on double click?

In Ubuntu 16.04 LTS unlike in previous LTSs executable shell script files when double clicked open automatically for editing instead of seeing a popup asking what to do with them.

To restore the confirmation popup do as it is said in this askubuntu post: make sure your file manager supports executing files:
$ gsettings set org.gnome.nautilus.preferences executable-text-activation ask
  1. Open dconf Editor
  2. Navigate to org.gnome.nautilus.preferences
    1. Set the 'executable-text-activation' to 'ask'

2017. február 19.

Installing Ubuntu 16.04 LTS Xenial Xerus

I ran into a couple of problems while trying to install the new LTS on my HPQ TC4400 laptop.
It had the 12.04 LTS installed, and had the home directory on a separate partition.

1. problem: no booting from pendrive
I tried different pendrives (2, 4, 8 GB), different USB slots (there are 3 on my machine) and different Ubuntu versions (12.04, 14.04, 16.04).
The problem I ran into is this:
gfxboot.c32: not a COM32R image
So first I tried to create startup disks on my desktop 12.04 on different pendrives with 16.04 and 14.04 images. They all resulted in this error. I went with the "live" command for 16.04. But one pendrive did not even start up the live session, while another did. Once I was in live, I tried to install 16.04, with the same distribution of the hard drives as I had before. It seemed to be okay. However when I started it and logged in, the system never loaded. Instead I got this disrupted background image flashing in different resolutions for until I had enough and turned off the machine.
Next I tried creating the startup discs on the 16.04 live session. The 14.04 pendrive booted alright compared to the one created on 12.04, but then the installation failed, and then booting also wasn't smooth anymore.
Next I reinstalled the 12.04, however it had issues with settings already existing on the home partition. The system did not load properly throwing errors in ma face.

Luckily I just got a spare 500GB hard drive, switched it with the old one and went again for 16.04 with the strange boot interface typing "live" in, and then installing from the live session.
It turned out okay so far.

My conclusion is that the settings in the home partition somehow interfered with the newly installed OSs, but really I have no clue what happened and why.