warvariuc's questions

I have Kubuntu 15.10 with kubuntu-ppa/backports and kubuntu-ppa/ppa enabled. Yesterday some updates came (5.5.3 I guess). Now I cannot log in:

.xsession-errors

This application failed to start because it could not find or load the Qt platform plugin "xcb".

Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.

Reinstalling the application may fix this problem.
startkde: Starting up...
dbus-update-activation-environment: warning: error sending to systemd: org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.freedesktop.systemd1 exited with status 1
kdeinit5: preparing to launch 'libkdeinit5_klauncher'
kdeinit5: Launched KLauncher, pid = 2221, result = 0
This application failed to start because it could not find or load the Qt platform plugin "xcb".

Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.

Reinstalling the application may fix this problem.
kdeinit5: Communication error with launcher. Exiting!
kdeinit5_wrapper: Warning: connect(/run/user/1000/kdeinit5__0) failed: : Connection refused
This application failed to start because it could not find or load the Qt platform plugin "xcb".

Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.

Reinstalling the application may fix this problem.
Aborted
/usr/bin/startkde: 1: /usr/bin/startkde: kreadconfig5: not found
startkde: Shutting down...
kdeinit5_wrapper: Warning: connect(/run/user/1000/kdeinit5__0) failed: : Connection refused
Error: Can not contact kdeinit5!
startkde: Done.

I have installed manually libkf5config-bin, and kreadconfig5 is now available, but the message "This application failed to start because it could not find or load the Qt platform plugin "xcb"." still persists not allowing me to log in.

Should I wait for the next updates? Or I can fix this now?

I think I did a mistake when I decided to use Btrfs. I am not using any of its features, but now have troubles with not enough space. I did

sudo btrfs balance start / -v

as suggested in some sources, but still have little space available:

$ sudo btrfs fi df /    
Data, single: total=102.00GiB, used=99.55GiB
System, single: total=32.00MiB, used=16.00KiB
Metadata, single: total=2.00GiB, used=762.44MiB
unknown, single: total=256.00MiB, used=0.00

A source suggests to remove snapshots. I found one candidate:

$ sudo btrfs subvolume list /
ID 257 gen 390597 top level 5 path @
ID 258 gen 390597 top level 5 path @home
ID 317 gen 390480 top level 5 path @apt-snapshot-release-upgrade-utopic-2014-10-23_20:38:40

Is it safe to delete @apt-snapshot-release-upgrade-utopic-* snapshot?

Note: I am using eCryptFS (not sure if this matters in this case).

I have encrypted home directory, which has drwx------ permissions after mounting.

Is there a possibility to have Public directory inside it which is accessible by other users?

As I understand, it's not possible to have such directory inside $HOME without changing the parent directory permissions as well.

I guess the way is to create the folder in some other place (e.g. /home/shared/), make me the owner, give the appropriate permissions to other users and create a symlink from my home directory to it?

I found a tutorial which might not be up to date, but I could not find a better one.

It states several times:

This directory is then automatically encrypted when you log off.

Is this true? If yes, doesn't this mean that power loss can expose private data to someone who has physical access to the hard-drive?

I've just upgraded to Firefox 34, but cannot see "Hello" icon on Firefox toolbar.

I could not find any info on that in Internet.

There is no "Hello" icon there in "Additional Tools and Features"

I have Kubuntu 14.04 and just installed the newest updates. Looking at the process list I see baloo indexer running.

I could not find a checkbox in Baloo settings to turn off the indexing.

I have a MacBook Pro notebook with native resolution of 2560x1600 which makes all my desktop details unreadable. I tried increasing DPI, but icons remain small, so I decided to decrease display resolution. I thought that resolution of 1280x800 would work the best, as 4 pixels of the native resolution would become one pixel in the lower resolution. But 1280x800 is not available to set:

$ xrandr -q
Screen 0: minimum 320 x 200, current 2560 x 2538, maximum 32767 x 32767
eDP1 connected 1440x900+0+1638 (normal left inverted right x axis y axis) 286mm x 179mm
   2560x1600      60.0 +
   2048x1536      60.0  
   1920x1440      60.0  
   1856x1392      60.0  
   1792x1344      60.0  
   1920x1200      60.0  
   1920x1080      59.9  
   1600x1200      60.0  
   1680x1050      60.0     59.9  
   1600x1024      60.2  
   1400x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9* 
   1280x960       60.0  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
DP1 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440      60.0*+
   1280x720       59.9  

So I set resolution of 1440x900 and the desktop is blurry.

I tried setting the native resolution with xrandr --output eDP1 --scale .5x.5 but the effect s not any better.

How to set 1280x800 resolution which is 1/4 size of the native resolution of 2560x1600 to make my screen look better?

UPDATE:

It's strange: when I boot to MacOS and try changing retina display resolution to scaled it also offers 1440x900, but the resulting picture is very good.

I have installed an EnhanceIO SSD cache on my notebook.

EnhanceIO supports three caching modes: read-only, write-through, and write-back.

Read-only caching mode causes EnhanceIO to direct write IO requests only to HDD. Read IO requests are issued to HDD and the data read from HDD is stored on SSD. Subsequent Read requests for the same blocks are carried out from SSD, thus reducing their latency by a substantial amount.

In Write-through mode - reads are handled similar to Read-only mode. Write-through mode causes EnhanceIO to write application data to both HDD and SSD. Subsequent reads of the same data benefit because they can be served from SSD.

Write-back improves write latency by writing application requested data only to SSD. This data, referred to as dirty data, is copied later to HDD asynchronously. Reads are handled similar to Read-only and Write-through modes.

My cache has default type of Write-Through. I am thinking that Read-Only mode should be almost the same fast and would save my SSD from degrading, because of avoiding unnecessary writes to it.

Am I correct?

I have a notebook on which I on want to install Ubuntu 13.10 in dual boot with Window 8.1. It has an 500GB HDD, and a 24GB SSD used as cache in Windows. In Windows I disabled ExpressCache and unformatted the SSD.

Now I am looking for reasonable way to partition my drives while installing Ubuntu to make use of the SSD.

I looked on the internet, and there are different setups people use.

1. Using flashcache/bcache. This is the same as ExpressCache in Windows. Advantages: Everything is cached and is cached automatically. Disadvantages: requires advanced setup; also, I'ma afraid something can break when Linux Kernel is upgraded.

2. Putting / on SSD and /home in HDD. Advantages: very simple and robust setup. Disadvantages:

   I think I would put the /home directory on the SSD, but for most directories, especially the ones with large files, I would simply have a symbolic link to whatever contains the files. This way, you can keep your settings, and the browser cache, etc on the SSD, but put the pictures, sounds, documents, etc on whatever disk you want, which can easily be changed by changing the links.

3. Putting / and /home on SSD, while making symbolic links for Downloads, Videos, .wine, etc. to HDD. Advantages: maximum cache. Disadavantages: micromanagement - to many things to fiddle with.

4. Where to put swap partition?

https://askubuntu.com/a/289202/7064

Also, if you plan for a swap partition, put in on the SSD.

https://askubuntu.com/a/62161/7064

Do not put swap on the ssd. Put it on the hdd.

https://askubuntu.com/a/20154/7064

I wouldn't care too much about putting a swap-partition on a SSD. The swap is, like said before, only used if there's no RAM left. But then there are "few" sequential writes and "many" random reads. That's exactly a form of usage SSDs excel in.

What storage setup are you using? What are other advantages/disadvantages in each of the setups?

Also, though people say that modern SSDs are good with a lot of writes, I still don't trust them, especially as a read from my comments on my notebook that the SSD in it breakes quite often.

I am using Droid fonts were possible. I have KDE.

Droid fonts look perfect with full hinting, but Ubuntu font do not.

Ubuntu font looks good with no or slight hinting, but then Droid fonts look bad.

Is there a possibility to specify hinting type per font family?

I tried the following in fonts.conf, but it doesn't work:

 <match target="pattern" name="family">
  <test name="family" qual="any">
   <string>Ubuntu</string>
  </test>
  <edit binding="strong" mode="assign" name="hintstyle">
   <const>hintnone</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="rgba">
   <const>none</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hinting">
   <bool>true</bool>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hintstyle">
   <const>hintfull</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="antialias">
   <bool>true</bool>
  </edit>
 </match>

Trying to capture screen to video file encoded with lossless x264:

vic@vic-X202E ~/Desktop » ffmpeg -f x11grab -r 15 -s 1366x768 -i :0.0 -sameq -vcodec libx264 -preset:v ultrafast test.mkv
ffmpeg version 0.8.4-6:0.8.4-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers
  built on Nov  6 2012 16:51:11 with gcc 4.7.2
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
[x11grab @ 0xc2bf60] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1366 height: 768
[x11grab @ 0xc2bf60] shared memory extension  found
[x11grab @ 0xc2bf60] Estimating duration from bitrate, this may be inaccurate
Input #0, x11grab, from ':0.0':
  Duration: N/A, start: 1357648973.267658, bitrate: 503562 kb/s
    Stream #0.0: Video: rawvideo, bgra, 1366x768, 503562 kb/s, 15 tbr, 1000k tbn, 15 tbc
Unrecognized option 'preset:v'
Failed to set value 'ultrafast' for option 'preset:v'

Another try:

vic@vic-X202E ~/Desktop » ffmpeg -f x11grab -r 15 -s 1366x768 -i :0.0 -sameq -vcodec libx264 -preset ultrafast test.mkv  
ffmpeg version 0.8.4-6:0.8.4-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers
  built on Nov  6 2012 16:51:11 with gcc 4.7.2
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
[x11grab @ 0x2482f60] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1366 height: 768
[x11grab @ 0x2482f60] shared memory extension  found
[x11grab @ 0x2482f60] Estimating duration from bitrate, this may be inaccurate
Input #0, x11grab, from ':0.0':
  Duration: N/A, start: 1357648985.325860, bitrate: 503562 kb/s
    Stream #0.0: Video: rawvideo, bgra, 1366x768, 503562 kb/s, 15 tbr, 1000k tbn, 15 tbc
Unrecognized option 'preset'
Failed to set value 'ultrafast' for option 'preset'
vic@vic-X202E ~/Desktop » 

Something broken? Using Kubuntu 12.10.

I could not find a screenshot, but i've seen a colleague of mine doing this:

he has a terminal open in his MacBook Air, starts typing a file name, presses Tab and is given a list of suggestions, like in linux, but has a possibility to move a cursor to select a suggestion. Then he presses Enter and the selected suggestion is entered automatically.

Is there such a think for Ubuntu? KDE?

In Kubuntu 12.04 using man fonts.conf i read:

 ~/.fonts.conf is the conventional location for per-user font configuration,
 although the actual location is specified in the global fonts.conf file.

But in /etc/fonts/fonts.conf i cannot find any settings giving me that local conf file path.

I am asking this, because in 12.10 the same command give me:

reading configurations from ~/.fonts.conf is deprecated

So i want to read user font conf file location from the global conf file.

I want where possible Droid fonts to be used. So i created ~/.fonts.conf with this content:

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
  <alias>
    <family>serif</family>
    <prefer>
      <family>Droid</family>
    </prefer>
  </alias>
  <alias>
    <family>sans-serif</family>
    <prefer>
      <family>Droid</family>
    </prefer>
  </alias>
  <alias>
    <family>sans</family>
    <prefer>
      <family>Droid</family>
    </prefer>
  </alias>
  <alias>
    <family>monospace</family>
    <prefer>
      <family>Liberation</family>
    </prefer>
  </alias>
 <match target="font">
  <edit mode="assign" name="rgba">
   <const>none</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hinting">
   <bool>true</bool>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hintstyle">
   <const>hintmedium</const>
  </edit>
 </match>
 <dir>~/.fonts</dir>
 <match target="font">
  <edit mode="assign" name="antialias">
   <bool>true</bool>
  </edit>
 </match>
</fontconfig>

But i get this in the console:

vic@wic:~/Documents$ fc-match sans
Fontconfig warning: "/etc/fonts/conf.d/50-user.conf", line 9: reading configurations from ~/.fonts.conf is deprecated.
DejaVuSans.ttf: "DejaVu Sans" "Book"

I tried restarting computer, but i get the same result.

How do i force Ubuntu to use Droid fonts where possible?

Do you know of any app that can take a screenshot using a keyboard shortcut, open a window for selecting a region of the screenshot and upload it to a hosting like imgur?

Preferably for KDE.

I want t try overlay scrollbars in Eclipse. I am using KDE.

How do I enable overlay scrollbars in GTK apps under KDE?