Debugging Skype crash problems on Ubuntu 10.04 Lucid Lynx Linux

Symptoms: Your Skype crashes on incoming chat message or if you try to open a contact info / chat message – usually this leads to a crash on Skype start-up because there are always incoming chat messages in a queue.

Skype is not really helpful regarding how to get meaningful log information from the client, but it is possible.

Create a log directory

mkdir ~/.Skype/Logs

Run Skype from the command line and open a chat window so that it crashes

moo@murskaamo:~$ skype
Aborted

Now there should be log data available

moo@murskaamo:~$ ls -lh ~/.Skype/Logs/
total 724K
-rw-r--r-- 1 moo moo 607K 2010-07-16 11:10 skype_20100716-1110.log
-rw-r--r-- 1 moo moo 116K 2010-07-16 11:10 skype_20100716-1110.trace.txt

However, those log files are little useful for anybody except Skype developers as they are encrypted. Your only hope is to submit them to  a Skype bug tracker and hope that someone answers you something meaningful. The guidelines how to create a bug report and how they are processed is little unclear – there doesn’t seem to be clear announcement from Skype whether they process  these reports or not.

The crashes probably are due to incompatible system library versions / bugs in them. Try downloading static Skype versions which does not use system libraries.

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Easily install all Python versions under Linux and OSX using collective.buildout.python

Here are short instructions how to install all versions (2.4, 2.5, 2.6, 2.7 and 3.1) of Python interpreters on UNIX system. The instructions were tested on Ubuntu 10.04 Lucid Lynx Linux but should work on other systems as is. The installation is based of downloading, compiling and installing different Pythons and their libraries using buildout tool. A buildout configuration for doing this is maintained by a Plone community.

This buildout is especially useful to get Python 2.4 properly running under the latest Ubuntu 10.04 Lucid Lynx. This is because Ubuntu repositories won’t ship with Python 2.4 packages anymore.

The installation will also include static compilation of some very popular libraries. These are dependencies for other Python packages including, but not limited, to

• libjpeg
• Python imaging library
• readline

Prerequisites

• Some Python version is installed (OS default)
• GCC compiler is installed (sudo apt-get install build-essential)
• Subversion tool is installed (sudo apt-get install subversion)

Running it

svn co http://svn.plone.org/svn/collective/buildout/python/
cd python
python bootstrap.py
bin/buildout

Using it

All Pythons are under virtualenv installations. This means that you can activate one Python configuration for your shell once easily (python command will run under different Python versions).

Activating Python 2.4

source python/python-2.4/bin/activate
(python-2.4)moo@murskaamo:~/code$ python -V
Python 2.4.6

Check that Python Imaging Library works

python
Python 2.4.6 (#1, Jul 16 2010, 10:31:46)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import PIL

(No exceptions raised, Python Imaging Library works well).

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Changing the location of Ubuntu 10.04 Lucid Lynx notification bubble to a different corner

Ubuntu notifications, those grey bubbles for incoming instant messages and such, are in the top right corner under the system tray area by default. Many applications, like Google Chrome browser, place lots of controls there and notifications might block them. Also, you might prefer some other corner due to your personal taste. The application for responsible for those bubbles is called notify-osd.

Here are instructions how get a custom notification-osd which can read a config file where you can specify settings for the notifications. Though it requires you to install a custom notify-osd version, the instructions are plain and simple. For less hardcode users, there also exists a version with graphical user interface to configure notify-osd.

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How to install Joomla! on your Ubuntu/Linux server with basic security

The instructions may apply for other versions too.

Prerequisitements

What you need to have in order to use this how to

• Basic UNIX file permissions knowledge
• Basic UNIX shell knowledge
• You have a Linux server (Ubuntu / Debian) for which you have root user access and you plan to use this server to host one or several Joomla! sites
• Apache and MySQL instaleld on your server

User setup

Set-up an UNIX user on a dedicated server for Joomla! hosting. The user can SSH in the box and write to his home folder, /tmp and /var/www site folder.

We create a user called “user” in this instructions. Replace it with the username you desire. We also use the example site name (www).yoursite.com.

sudo adduser user # Asks for the password and created /home/user

sudo mkdir /var/www/user
sudo chmod -R user:user /var/www/user # Only user has writing access to this folder

Setup MySQL user account

Install MySQL as per Debian/Ubuntu instructions.

Login as MySQL admin user (may vary depending how your MySQL is configured). Note that first you will be asked for sudo password, then for MySQL administrative user password.

sudo mysql -u admin -p

CREATE DATABASE user DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_general_ci;

GRANT ALL ON user.* TO 'user'@'localhost' identified by 'zxc123zxc'; 

Extract Joomla! installation files

Enter the folder which will contain web site PHP files.

sudo -i -u user # pose yourself as UNIX user who runs the site

cd /var/www/user

wget http://joomlacode.org/gf/download/frsrelease/12350/51111/Joomla_1.5.18-Stable-Full_Package.zip

unzip Joomla_1.5.18-Stable-Full_Package.zip

exit

Set file permission

Note that during Joomla’s browser based installation Apache’s www-data must have write access to folder in order to create configuration.php file. We will later remove this access right.

We will set Joomla! files under UNIX group group www-data so that Apache can read them. Certain files are set to be writable. This must be done as root user.

sudo chown -R user:www-data /var/www/user # Make user group to www-data

sudo chmod g+wrx /var/www/user # Read only access to www-data user. Write access for installation, will be later removed.

Now ls -l command in /var/www/user should give you something like this for fil masks:

drwxr-xr-x 11 user www-data    4096 2010-05-28 10:22 plugins
-rwxr--r--  1 user www-data     304 2010-05-28 10:21 robots.txt
drwxr-xr-x  6 user www-data    4096 2010-05-28 10:22 templates

Creating Apache configuration

sudo nano /etc/apache2/sites-enabled/yoursite.conf

   ServerName yoursite.com
   ServerAlias www.yoursite.com
   ServerAdmin info@yourcompany.com

   LogFormat       combined
   TransferLog     /var/log/apache2/yoursite.log

   # Make sure this virtual host if capable of executing PHP5
   Options +ExecCGI
   AddType application/x-httpd-php .php .php5

   # Point to www folder where Joomla! is extracted
   DocumentRoot /var/www/yoursite

   # Do not give illusion of safety
   # as PHP safe_mode really is a crap
   # and only causes problems
   php_admin_flag safe_mode off

   #
   # This entry will redirect traffic www.yoursite.com -> yoursite.com
   # Assume mod_rewrite is installed and enabled on Apache
   # 301 is HTTP Permanent Redirect code
   RewriteEngine On
   RewriteCond %{HTTP_HOST} ^www\.yoursite\.com [NC]
   RewriteRule (.*) http://yoursite.com$1 [L,R=301]

</VirtualHost>

Faking the DNS entry

sudo gedit /etc/hosts

# Force this hostname to go to your server public IP address from your local computer

123.123.123 yoursite.com www.yoursite.com

Start Joomla! browser based installation

http://yoursite.com

Secure the configuration

sudo chmod -R g-w /var/www/user # Remote write permission
sudo rm -rf /var/www/user/installation # Remove installation directory
# Add write permission to folders which contain writable files
sudo chmod -R g+x /var/www/user/logs
sudo chmod -R g+x /var/www/user/images
sudo chmod -R g+x /var/www/user/tmp
sudo chmod -R g+x /var/www/user/images

Setting up htaccess files

Joomla! comes with a sample htaccess file which has some security measurements by having RewriteRules to prevent malformed URL access.

To install this file do the following

sudo -i
cd /var/www/user
cp htaccess.txt .htaccess
chmod user:www-data .htaccess # Set file permission to be readable by Apache and writable by the UNIX user

Then we create a .htaccess file which we will place in all folders with Joomla! write access to prevent execution of PHP files in these folders. First we create htaccess.limited file which we use as a template.

sudo -i
cd /var/www/user
nano htaccess.limited # Open text editor

Use the following htaccess.limited content

# secure directory by disabling script execution
AddHandler cgi-script .php .pl .py .jsp .asp .htm .shtml .sh .cgi
Options -ExecCGI -Indexes

And put the master template htaccess.limited  to proper places

cp htaccess.limited media/.htaccess
chown -R user:www-data media/.htaccess 

cp htaccess.limited tmp/.htaccess
chown -R user:www-data tmp/.htaccess 

cp htaccess.limited logs/.htaccess
chown -R user:www-data logs/.htaccess

cp htaccess.limited images/.htaccess
chown -R user:www-data images/.htaccess

Start using the site

Setting outgoing email

Test outgoing email

Maintaining file permission

sudo usermod -a -G www-data user # Add user to www-data group so that it can set group permissions

sudo -i -u user # Login as your UNIX user
chgrp -R www-data templates libraries # Fix group ownership
chmod -R g+rx libraries templates # Set read access for the group

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ssh-copy-id for OSX

ssh-copy-id is a handy shell script which allows you to easily copy your public key to a remote server, so that you don’t need type in password every time you take SSH connection into that box. Ubuntu and the latest Linux distros ship ssh-copy-id with the ssh client installation. However, for OSX you need to manually drop this little script into your /usr/bin.

The usage is simple. Just run:

ssh-copy-id remotebox.com

to copy your public SSH key to remotebox.com. After that

ssh remotebox.com

shoud ask no password.

Working installation instructions for ssh-copy-id on OSX are in Chris Pitzer’s blog.

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Could not open a connection to your authentication agent on Ubuntu 9.10 Linux

I just run into this when tried to enable Github SSH to perform git push.

The workaround is to run command

`eval ssh-agent`

Which sets series on environment variables making ssh-add to work.

I don’t know why this doesn’t work anymore – I am quite sure it worked on earlier Ubuntu versions out of the box.

Related bug report.

Profiling PostgreSQL database

This blog post will have some short notes about monitoring and profiling PostgreSQL databases.

pgtop

pgtop provides UNIX top command like user interface for PostgreSQL. pgtop command is available as Perl CPAN module.

How to install Perl CPAN modules as non-root user on Ubuntu (note: when it prompts to run sudo, answer no).

To install pgtop install following CPAN modules first: Term::ANSIColor, Term::ReadKey, DBD::Pg

perl -MCPAN -Mlocal::lib -e 'CPAN::install(DBD::Pg)'
perl -MCPAN -Mlocal::lib -e 'CPAN::install(Term::ReadKey)'
perl -MCPAN -Mlocal::lib -e 'CPAN::install(Term::ANSIColor)'

pgtop install instructions

pgtop manul

Running pgtop:

perl pgtop -d databasename -u yourdbuser -p yourdbuserpassword

pgfouine

pgfouine is a log analyzer for PostgreSQL.

Setting up multi-touch scrolling for Ubuntu 9.10 Karmic Koala Linux on Asus Eee 1005HA netbook

This post is specific to Asus Eee 1005HA netbook, but the technique explained here can be used on any computer having Synaptics touchpad.

Multi-touch gestures allow you to perform user interface actions by doing two finger gestures on touchpad. Apple introduced this feature on Macbooks and after you get used to it, it greatly enhances your web browsing on mouseless netbook. The most important gesture is scroll text by swiping the touchpad with two fingers.

Apple has also many patents related to the gestures so they are not enabled by default.

The real multi-finger touch support needs multi-finger aware (capacitive) touchpad. Most PC laptops are not equipped with one. Luckily some of the simple gestures, like two finger scrolling, can be emulated on normal pressure point sensitive touchpad via clever calculations and other tricks.

Note: Ubuntu HAL support for Synaptics seem to be broken. Only shell script at the end of the post will work. HAL options in FDI file are being ignored.

Setting up Synaptics driver

Type in terminal

gksudo gedit /etc/hal/fdi/policy/11-x11-synaptics.fdi

Create and save file with this content:

<?xml version="1.0" encoding="ISO-8859-1"?>
<deviceinfo version="0.2">
 <device>
   <match key="info.capabilities" contains="input.touchpad">
       <merge key="input.x11_driver" type="string">synaptics</merge>
       <merge key="input.x11_options.SHMConfig" type="string">On</merge>

       <merge key="input.x11_options.EmulateTwoFingerMinZ" type="string">40</merge>
       <merge key="input.x11_options.VertTwoFingerScroll" type="string">1</merge>
       <merge key="input.x11_options.HorizTwoFingerScroll" type="string">1</merge>
       <merge key="input.x11_options.TapButton1" type="string">1</merge>
       <merge key="input.x11_options.TapButton2" type="string">3</merge>  <!--two finger tap -> middle clieck(3) -->
       <merge key="input.x11_options.TapButton3" type="string">2</merge>  <!--three finger tap -> right click(2). almost impossible to click -->
   </match>
 </device>
</deviceinfo>

This allows us to use synclient utility to watch touchpad real-time data in console window.

Now restart X

sudo /etc/init.d/gdm restart

And open terminal again.

Type in command

synclient -m 100

And you should see data like this scrolling in the terminal:

129.355  2912 3469  59 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 129.455  2952 3529  59 1  4  1 0 0 0 0  00000000   0  0  0   0   0
 time     x    y   z f  w  l r u d m     multi  gl gm gr gdx gdy
 129.555  3283 3516  60 1  4  1 0 0 0 0  00000000   0  0  0   0   0
 129.656  3928 3517  60 1  4  1 0 0 0 0  00000000   0  0  0   0   0
 129.756  4364 3637  60 1  4  1 0 0 0 0  00000000   0  0  0   0   0
 129.856  4020 3329  49 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 129.956  3634 3122  58 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.057  3320 2957  60 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.157  2779 3312  61 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.257  2557 3739  61 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.358  2636 3485  39 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.458  2659 3104  60 1  4  0 0 0 0 0  00000000   0  0  0   0   0
 130.558  2671 2988  60 1  4  0 0 0 0 0  00000000   0  0  0   0   0

f column tells the number of fingers. w is the touched area width. z is the pressure.

If you put two fingers on touchpad and you see value f=2 then your hardware has multi-touch aware touchpad. Unfortunately Asus Eee 1005HA doesn’t seem to have one

Emulation approach

Synaptics driver can emulate two-finger touch with the following conditions

• Touched area width exceeds certain threshold (min width)
• Touch pressure exceeds certain thresholds

When the conditions are met the driver thinks “Wow looks this guy is pressing us really hard. maybe he is using two fingers?” Note that touchpad values are touchpad specific and values applying for one model don’t work on another computer.

Synaptics driver settings are described here. Synaptic driver settings can be modified run-time using xinput command. Run synclient -m 100 in one terminal window and change threshold values in other until you find correct emulation parameters for your laptop. Below is my xinput tests. Test scrolling on Firefox and any long web page.

moo@huiskuttaja:~$ xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Width" 32 7
moo@huiskuttaja:~$ xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Pressure" 32 280
moo@huiskuttaja:~$ xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Width" 32 11
moo@huiskuttaja:~$ xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Pressure" 32 50
moo@huiskuttaja:~$

Looks like the following parameters are good for two finger emulation for Asus Eee 1005HA:

• Width: 8
• Pressure (Z): 10

You can also use command synclient -l to dump the current settings.

Below is the final script you need to run during log-in (see note about broken HAL at the beginning of the post):

#!/bin/sh

#!/bin/sh
#
# Use xinput --list-props "SynPS/2 Synaptics TouchPad" to extract data
#

# Set multi-touch emulation parameters
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Pressure" 32 10
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Width" 32 8
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Two-Finger Scrolling" 8 1
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Scrolling" 8 1 1

# Disable edge scrolling
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Edge Scrolling" 8 0 0 0 

# This will make cursor not to jump if you have two fingers on the touchpad and you list one
# (which you usually do after two-finger scrolling)
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Jumpy Cursor Threshold" 32 110

Jumpy cursor after two finger scroll

When you do a two-finger scroll and lift your one finger before the other the mouse cursor/scrolling may jump. Synaptics driver does not seem to have an option to filter out this bad event. If anyone knows solution for this please comment.

Other resources

• Linux Multi-Touch is a project to collect set of Perl scripts related to multi-touch events. If you want to customize your multi-touch experience and you have some development insight, this is the place to begin.
• Notes about multi-touch emulation (see the last comment).
• Diagnosing multitouch support and editing HAL files.
• Related idea on Ubuntu Brainstorm.
• Synaptics X11 driver source. Synaptics driver project page. Looks like there is no one central figure behind it, except for maintaining, and big bunch of patches from distributors.

Autoconfiguring dual monitors on Ubuntu

The following shell script is a helper script for laptop users who connect an external monitor now and then to their laptop. Since Ubuntu does not provide clever ways to arrange desktop or detect connected displays, you need to run the script from terminal when you change your monitor configuration.

• detect the numbers of monitors you have attached
• Activate the second (external) monitor if there are two monitors
• Use the external monitory as the primary display, otherwise use internal display as a primary display
• Move your taskbars to the primary display

It is based on disper tool by Willem van Engen. For now (2009), it’s nVidia only. ATI support could be possible.

#!/bin/sh
#
# Detect displays and move panels to the primary display
#
# Copyright 2009 Twinapex Research
#
# Author <mikko.ohtamaa@twinapex.com>
#

# disper command will detect and configure monitors
disper --displays=auto -e

# parse output from disper tool how many displays we have attached
# disper prints 2 lines per displer
lines=`disper -l|wc -l`

display_count=$((lines / 2))

echo $display_count

echo "Detected display count:" $display_count

# Make sure that we move panels to the correct display based
# on the display count
if [ $display_count = 1 ] ; then
   echo "Moving panels to the internal LCD display"
   gconftool-2 \
        --set "/apps/panel/toplevels/bottom_panel_screen0/monitor" \
        --type integer "0"
   gconftool-2 \
        --set "/apps/panel/toplevels/top_panel_screen0/monitor" \
        --type integer "0"
else
   echo "Moving panels to the external display"
   gconftool-2 \
        --set "/apps/panel/toplevels/bottom_panel_screen0/monitor" \
        --type integer "1"
   gconftool-2 \
        --set "/apps/panel/toplevels/top_panel_screen0/monitor" \
        --type integer "1"
fi

How to encode h264 video files for Nokia Series 60 standalone playback

Bored with Spiderman 3 which came with your Nokia N95 8 GB? This guide shortly tells how to get movies into your N95 on Ubuntu Linux using ffmpeg video encoder. The aim is to encode video suitable for playback from Nokia N-series (N95, N78, others) mobile phone memory card. We use h264 + AAC codecs which provides the best quality/compression rate for Nokia phones currently.

Ubuntu does not distribute proprietary codes. First thing you need to do is to rebuild ffmpeg.  Since Ubuntu 8.04 Hardy Heron ships with ffmpeg from 2007, which is aeons old in video codec years, you need to build libx264 and ffmpeg from SVN sources. Here are detailed, valid, instructions. Note that FFMPEG trunk is not currently stable (September 2008), so you need to use revision 15261 which needs this little patch. Indeed, this is a very difficult month to start your career in the dark world of video encoders.

To make it legal and support open source codec development,  please pay for your codecs.

Then we use this guide by Robert Swain. We have a tiny sub 2,4″ screen, we do not care about the quality and do one pass encoding. By empirical research, I have found that the following MPEG-4 profile parameters are compatible with N95 8 GB and provide the optimal result. You can vary video and audio bitrate depending on your taste.

Here is a script which recursivelu encodes all detected video files suitable for mobile format:

#!/bin/sh
#
# Optimal movie encoding for Nokia N-series mobile phones
#
# Copyright 2008 Red Innovation Ltd.
#
# Say hi if you find this useful.
# We do some professional mobile video publishing, so if you
# need a helping hand please call us.
#
# Usage: Run encode.sh in any folder and all video files are recursively converted to mobile phone suitable format
#
# Note: We expect all the source material be in 16:9 aspect ration
#
# Also see http://www.nseries.com/index.html#l=support,search,faq,general,video%20encoding,53848
#

VIDEO_BITRATE=300k

AUDIO_BITRATE=72k

# Assume locally build ffmpeg + x264 in /usr/local/bin
# http://ubuntuforums.org/showthread.php?t=786095
export LD_LIBRARY_PATH=/usr/local/lib

# Search all source AVI, MPG and WMV video files
# Place all encoded files to the same folder with the source, with added .mp4 extension
find . -iname "*.avi" -or -iname "*.wmv" -or -iname "*.mpg" | while read src ; do
        srcfile=`basename "$src"`
	srcfolder=`dirname "$src"`
	dstfile="$srcfolder"/"$srcfile".mp4

	# The magical string!
	# Size and cropping is for 16:9 source material, so that 320:240 display will have black bars.
	# Fex pixels off... note that h264 sizes must be multiplies of 16, use 256x144 for streaming
	# N95 RealMedia player does not seem to respect MPEG-4 embedded aspect ration info.
	/usr/local/bin/ffmpeg -y -i "$srcfile" -acodec libfaac -ab $AUDIO_BITRATE -s 320x176 -aspect 16:9 -vcodec libx264 -b $VIDEO_BITRATE -qcomp 0.6 -qmin 16 -qmax 51 -qdiff 4 -flags +loop -cmp +chroma -subq 7 -refs 6 -g 250 -keyint_min 25 -rc_eq 'blurCplx^(1-qComp)' -sc_threshold 40 -me_range 12 -i_qfactor 0.71 -directpred 3 "$dstfile"

done