GnuPG In 10 Minutes


If you need to secure communication or encrypt personal / sensitive data, GnuPG is the tool. Its free, and available for download from Gnu's Website or install from Debian repositories.

GnuPG is a free clone of PGP (PrettyGoodPrivacy), cryptographic software.

To find it on Debian, do:

aptitude search gnupg

To install:

aptitude install gnupg

To use GnuPG first, you generate your key:

gpg --gen-key

Please select what kind of key you want:
   (1) RSA and RSA (default)
   (2) DSA and Elgamal
   (3) DSA (sign only)
   (4) RSA (sign only)
Your selection? 

Select # 1

RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 

Accept and press [ Enter ]

Please specify how long the key should be valid.
      0 = key does not expire
        = key expires in n days
      w = key expires in n weeks
      m = key expires in n months
      y = key expires in n years
Key is valid for? (0) 
Key does not expire at all
Is this correct? (y/N) 

Press Y

You need a user ID to identify your key; the software constructs the user ID
from the Real Name, Comment and Email Address in this form:
    "Heinrich Heine (Der Dichter) "

Real name: [ Enter your name here ]
Email address: [ Enter your email address here ]
Comment: [ Enter a comment or leave blank ]
You selected this USER-ID:
    "Your Name "

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? 

[ Press 'O' to accept settings ]

You need a Passphrase to protect your secret key.

[ Type a memorable phrase. You will need it later. ]

GnuPG will generate and display your key. Something like:

pub   2048R/8E6D74A2 2010-12-31
uid                  Your Name
sub   2048R/AD17E388 2010-12-31

The first line displays my key: 8E6D74A2. 

First entry identifies my public key: pub. 
I used 2048 bits to generate the key: 2048R/
The date my key was created: 2010-12-31

You can see my key is 8E6D74A2.

To encrypt a file:

gpg --output myfile.gpg --encrypt --recipient myfile.txt

GnuPG creates an output file called myfile.gpg which is encrypted and is generated for recipient using myfile.txt as input file.

To decrypt a file:

gpg --output myfile --decrypt myfile.gpg

You will need to give your memorable passphrase to decrypt the file.

To generate your public key:

gpg --armor --export myemail@address > mypubkey

Version: GnuPG v1.4.10 (GNU/Linux)


GnuPG generates my public key. I can display the key on my website, or send it via email to people I know and trust who wish to send me secure messages or files. 

That covers some uses of GnuPG. Its worth reading the online GnuPG Handbook.

Another Sacking For Benitez

San Siro Exit

I read ex-Livepool manager Rafa Benitez has been acrimoniously sacked by Inter Milan, after only six months in the job. Apparently El-President is a little unhappy that Inter lie 7th in the league. Why is that so bad? The season's not over yet.

Last year Inter finished top in Italian Seria A under 'The Special One' Jose Mourinho. Inter also picked up the Coppa Italia and to round the season off, they won the Champions League Cup. Quite a feat. Beating the best Europe can throw at them. It was the first time they have done the 'Treble'. Whether you like Mourinho or not, he gets results.

Benitez inherited a treble winning team, and has slowly squandered the winning momentum and mentality to sink to a lowly 7th place. Add to the mix, Benitez belligerent abrasive style, and you can understand why the Inter board were pleased to dump him.

In a way, its a re-run of what happened at Liverpool. Benitez inherited a good squad. He spent close to £300 Million and left behind a collection of mediocre players, that deserve Liverpool's current position of 9th place in the Premier League.

I watched incredulously and horror last season when, week after week Benitez wrestled with indecision on formation and team selection. After an outstanding performance one week, Benitez would drop key players for the next. Players whose game sparkled with flair, improvisation, commitment and work rate. Next game they warm the bench.

Game after game Benitez would switch formation. Change winning team selection. Move Gerrard out left or wide on the right wing. He would split partnerships that worked well, built a quiet understanding of each others game and support play.

Benitez laboured with zonal marking year after year, when it was obvious it did not work. Any one with a modicum of intelligence could see it was Liverpool's achilles heal. They leaked goals every week. Liverpool conceded more goals from set pieces (corners, and free kicks), than open play.

The news emanating from Italy, suggests Inter have suffered a similar fate.

Some online news sites suggest Premiere League vacancies will open to Benitez. They must be crazy. Has this guy's track record not spoken loudly enough? At best, he is mediocre, other times poor.

One part of Benitez game has remained consistently high. The Blame Game. It was something he played well. Throughout his time at Liverpool he always looked to blame others for a poor performance. Always looking for scape goats.

He argued the case for total control on team matters, player purchase, player sales, the youth team, and more. When he finally got the controll he yearned for, Liverpool bombed. He guaranteed a top 4 finish for Liverpool last season, but could only manage 7th place and effectively sealed his fate. Benitez blamed it on the owners lack of funds. He left behind him a Liverpool team in a desperately poor state, from which they have not recovered.

I'm pleased he's gone. Looks like the Italians feel the same way.

Aplay: Device Or Resource Busy

In Use

Went to check the sound setup on a Debian box and the sound app would not play. I kept getting the following error message:

aplay: audio open error: Device or resource busy

To extract info on the application hogging the sound device, do:

lsof | grep snd

This displayed:

xmms2d  31732  patrick   7u    CHR  116,9  0t0  3885 /dev/snd/controlC0

I could see evidence of the app that was blocking access. I had nothing obvious running, so I killed the process.

killall xmms2d

Then checked again.

lsof | grep snd

Nothing. Its clear.


Chrome Flashplayer 64-Bit Plug-In

Get Working

At the end of November, Adobe Labs announced the long awaited release of 64-bit flashplayer plug-in for Linux. I checked around and there are numerous HowTo's providing guidance on installing the new, improved plug-in on a Linux System. Most are wrong.

Advice includes downloading the Flashplayer-plug-in tarball and adding it to /usr/lib/. Ignore the advice. If you run Google's Chrome browser, here's how to install the new 64-bit flashplayer plug-in. I run Debian Linux.

Check /etc/apt/sources.list. You should have contrib non-free added:

$ cat /etc/apt/souces.list

If not, as root add contrib non-free to your repository. Here's my sources.list:

deb squeeze main contrib non-free
deb-src squeeze main contrib non-free

Yours should look similar. I run squeeze. After you confirm your repository has non-free added, close and save the file. 


# aptitude update

Next run:

aptitude install flashplugin-nonfree

Debian will download and auto install the flashplayer plug-in. Close and restart Chrome.

Go to and check it works.

Mine worked first time.


Add Slime To Emacs

Viscous Liquid Matter

SLime. Superior Lisp Interactive Mode for Emacs. Slime is an Emacs mode for editing and working with Common LISP. Setting up Slime is a breeze. Download the CVS file, gunzip it, move the directory and add the directory path to your dot.emacs file.

Slime recommends pulling down the latest CVS version.

After download, gunzip the file:

tar zvxf slime-current.tgz

Delete the tar file and move the unzipped directory.

rm slime-current.tgz

mv slime-2010-12-23 ~/prog/slime

Open dot.emacs file and add the following:

emacs ~/.emacs

(add-to-list 'load-path "~/prog/slime" ) ; slime directory
(require 'slime)

Close, restart Emacs, then start Slime mode:

M-x slime

You'll have the CLISP prompt:


Have a read of the Slime Online Manual. Its worth a look.


Gnu Screen

Multi Display

Gnu Screen is a faily low key application that is quite awesome in usage. Its functionality is grossly underrated, for such a powerful utility.

Taken from User Manual:

Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. There is a scrollback history buffer for each virtual terminal and a copy-and-paste mechanism that allows the user to move text regions between windows.

When screen is called, it creates a single window with a shell in it and then gets out of your way so that you can use the program as you normally would. Then, at any time, you can create new full-screen windows with other programs in them including more shells, kill the current window, view a list of the active windows, turn output logging on and off, copy text between windows, view the scrollback history, switch between windows, etc. All windows run their programs completely independent of each other. Programs continue to run when their window is currently not visible and even when the whole screen session is detached from the user's terminal.

When a program terminates, screen kills the window that contained it. If this window was in the foreground, the display switches to the previously displayed window; if none are left, screen exits.

If you have used Emacs, its very similar in user interaction, though functionality is very different.

Here are a few commands to get you going. You can find the rest and plenty of info at Gnu Screen Documents.

Start screen in an XTerm:

xterm screen

Auto start screen with XTerm:

xterm -e screen

Kill screen:

C-a C-\

Create a new window:

C-a C-c

Kill current window:

C-a C-k

Switch to next window:

C-a C-n

Switch to previous window:

C-a C-p

Toggle between windows:

C-a C-a

Name a window:

C-a A

Display screen list:

C-a C-w

Display interactive screen list:

C-a C-"

Clear the screen of text:

C-a C

That's all for now.

Microsoft Loves Linux

MS Linux

Out of curiosity, I wandered over to and ran a check on what servers Microsoft runs for its mail service. I queried Netcraft's database and ran a What's That Site Running? search. If you have never used it, give it a shot it turns up interesting results at times.

Anyhow, it seems Microsoft loves Linux so much, 18 of its 24 Hotmail servers run flavours of Linux OS. Only 6 of the 24 use Microsoft's own Windows Server 2003. Either MS can't afford the licence fees (they are very expensive) or Server 2003 can't handle the workload.

Microsoft's previous server offering, NT was prone to going zombie and a re-boot was the only way to bring it back to life.

Here's a capture a screen capture of the web page.

Would Ford Motor Company use GM vehicles for its operations?

It must be Linux love.

Ext4 File System

No More fsck

Recently did a clean install of Debian on a box and went with Ext4 file system on '/'. I read a while back that Fedora was shipping with Ext4 as default. Ubuntu being more conservative, stayed with Ext3.

I've had a few bad experiences in the past with exotic and novel technologies, I now take a more cautious path. Sometimes.

When I read Google was upgrading to Ext4, and hired the guy who played a main role in the development of Ext4, that was enough to persuade me. If it was good enough for big 'G', it was good enough for me.

One immediate benefit of Ext4; no more fsck. Those times when you reboot your machine and get the message:

/dev/sda1 been mounted 28 times without being checked, check forced.

Sit around twiddling your thumbs while fsck goes to work.

Ext4 is reputed to be faster than Ext3. Read the paragraph on the bitmap allocator.

In the meantime, check out the Ext4 Wiki page, which is packed with useful and meaningful info on the topic.


GRUB Multi Disk Multi Boot HowTo

Boot It

Recently installed Debian Linux on a new disk drive. I  still had my old drive with all my settings, data, files and so on. I want access to the old drive partitions while I worked on the new larger disk.

I could mount the old drive and access files from the mount, but I still wanted access to some applications and settings on the old disk. The easiest way to do this, was to Multi Boot from GRUB. I want the option to boot the old drive or the new.

If I need file access, I can do a temporary mount. The multi-boot set up allows me to work on the new disk at my leisure, till I'm ready to transfer files and wipe the old disk.

There's a lot of info on GRUB Multi Boot and a lot of HowTo's kicking around. Most are out of date. Many are misleading. Some refer to editing menu.lst or editing grub.conf. Both files no longer exist in GRUB. They have been replaced by grub.cfg, which is not to be manually edited. It states in grub.cfg.

Here's an excerpt:

$ cat /boot/grub/grub.cfg
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub

After installing Debian Linux on a new disk, including GRUB, here's the method for advising GRUB of your other disk and OS:

1. Shut down your system
2. Disconnect power from machine
3. Attach old disk
4. Connect power to your box
5. Boot system
6. Press del key to enter BIOS set up
7. Go to Boot section > Boot order
8. Ensure new disk is select as first boot device
9. Check old disk is recognized.
10. Save settings and exit
11. System reboots into your new disk
12. Fire up XTerm or other Terminal emulator
13. Become root user
14. dmesg | grep sd 

This will display all your disks. 
Your first boot device will be sda1 (your new disk).
Your old disk will be sdb1. This is for SATA disks. 
IDEs disks will be labelled hda1 and hdb1.

15. Run the update grub command and pass your old disk as argument

# update-grub /dev/sdb1

Grub will run off and do its thing

16. Reboot system

On system reboot, you should see your old disk lower down the menu boot. Select it and hit enter to boot off your old disk.

That's about it.

P.S. If you want to boot your new disk and need access to your files, you can do a temporary mount of your old disk. To create a mount point and mount your old disk, become root and do:

# mkdir /mnt/olddisk
# mount -t ext3 /dev/sdb1 /mnt/olddisk

If your not running ext3 on the old disk, replace with ext2 or fat, or whatever is there. If you run XP on the old disk it will have NTFS file system. You will need ntfs-3g utils to access NTFS files.

Do aptitude search ntfs for options and aptitude show for more info.


Identify Linux Hardware

What Is It?

Trying to identify the hardware in your box, when you run Linux, can be a wasted effort. Sure there are a few utils to identify some parts of your hardware setup, but its not comprehensive.

Apart from opening the case up and eye balling, how do you find out what you got under the 'hood?

lshw to the rescue. Its not installed as part of the Debian core, but it is available for download from Debian repositories.

You know the routine:

# aptitude install lshw

Once installed, run lshw as root user, to get a complete listing of your hardware setup.

The listing is comprehensive. I got 459 lines output when I ran it on my primary box. So I suggest piping it to a file where you can peruse it at your leisure, or just grep the hell out of it.

# lshw > hardware.list

That's about it.

*     *     *

StumpWM MPlayer Crash


I have been running StumpWM the keyboard oriented Window Manager for the last few days. It takes a little getting used to, but not much if you have used Emacs. It is very similar in usage to Emacs and Screen.

I like the concept and execution. Though as a finished product, some things are left for you to sort out. There are many key bindings left undone and  documentation is not extensive. You have to roll your sleeves up and set the bindings yourself in .stumpwmrc config file.

MPlayer crashes if you play a movie. I googled and discovered this was down to the way MPlayer defaults aspect ratio which, if not defined, results in a divide by zero error in CLISP.

I guess if you bypass default and pass an aspect ratio to MPlayer, that should get around the problem. I haven't tried this since stumpwm crashed last night I fired up and used XFCE4. I will try later and post an update.

To pass MPlayer an aspect ratio, do:

mplayer -aspect 2.4:1 nameofmovie.mpg

Here's the page I found describing the error.

MPlayer refuses to run under StumpWM

It looks like the developers are on the case and a fix may appear soon.


SSH Login No Password


To enable ssh login to other hosts on your network is pretty simple to set up. Generate a public key using ssh-keygen and copy the key to the hosts you want to access without a password. It that simple.

Here's how to do it:

1. Generate a public/private rsa key pair

ssh-keygen -t rsa

2. Give file location to save key. Accept default.

Press [enter]

3. Enter password for the key
Press [enter]

4. Enter same password:
Press [enter]

Your identification has been saved in /home/patrick/.ssh/id_rsa
Your public key has been saved in /home/patrick/.ssh/

5. Copy your public key.

Caution. Make sure you copy the right key. When ssh-keygen runs, it creates two keys: and id_rsa. is the public key. The one you share. The second key, id_rsa (no .pub extension) is your private key. If you copy the wrong key to the remote host, connection without password will not work.

cp ~/.ssh/

6. Copy public key to hosts on your network.

cat >> ~/.ssh/authorized_keys

7. Add your public key after any existing entries in authorized. Don't overwrite any.

8. Test it by logging in to one of the hosts on the network

ssh host

You're in with no password. If not, you carried out one of the steps wrong. Go back and check the matches the copy. Check the file is in the correct location: ~/.ssh. Check the file is correctly named: authorized_keys.

Added Bonus

Aside from being able to log in with no password, you can also copy files without needing to authenticate yourself.

*    *    *

Disable Root Login

More Secure

If you wanted to break into a system, one of the first ways to try is to find an account on the system. You could spend time guessing at users on the system or go for the one user on every Linux/Unix system. Root.

You know root exists on every system. It has to. All you need now is the password and your in. You're half way there.

To increase security, its best to disable root log in. Here's how.

As root open /etc/ssh/sshd_config and find the line PermitRootLogin.

emacs /etc/ssh/sshd_config
PermitRootLogin yes

Change 'yes' at the end of line to 'no', so it looks like this:

PermitRootLogin no

If the line has a hash mark '#' at start of line. Delete the '#' hash mark.

Save the file. Exit and restart sshd daemon.

/etc/init.d/ssh restart

Test it by trying to log in as root user. Log in should fail.


Using SSH And SCP


SSH and SCP command line tools are very similar in usage. Both utilise a secure connection. Data is encrypted to ensure secure transit. Passwords and other sensitive data is safe.

Using SSH

You must have a user account and password on the remote host or connection will fail. The remote host must be running ssh server. You can check for sshd using ps and grep.

ps -e | grep sshd
1493 ?        00:00:00 sshd

Another consideration is a firewall that blocks connections to port 22. If you cannot connect to the remote host, check firewall settings.

To log into a remote host using ssh, do:

ssh remotehost
myname@remotehost password:

Enter the password for the account on the remote host to gain access.

Using SCP

Using scp is similar to using ssh, in how you log in to the remote host. Once your in, the similarity ends.

To copy files from a remote host into the current directory do:

scp myname@remotehost:/filetocopy .

Notice the colon after the host name. Its important. Followed by the path to the file you want to copy. Finally at the end the dot '.' or period. That tells Linux to place the copied file in this directory. The dot is short hand for 'the current directory'.

Copying files from my box to a remote host is pretty much the same command, rehashed.

scp filetocopy myname@remotehost:/directory/to/copy/to

Give it a shot. See how ya go.

That's about it.


X Windows Lock Up

Kill It

Occasionally I've had X Windows lock up solid that no keyboard or mouse input has any effect.
So what do ya do, when X is totally unresponsive? How do ya free your machine?

You have a few options.

Remote ssh Login

If you have ssh installed and have access to another Linux box, you can remote login and kill X. When you ssh into yourbox, it will ask for your password. After entering correct password, do a ps -e| grep X to find Xorg process and kill the process id or run killall Xorg.

ssh yourbox
you@yourbox's password: 

ps -e |grep X
6408 tty8     00:08:42 Xorg

killall Xorg

That should do it.

Use Magic SysRq Key

You can use Magic SysRq Key to do a System Request and pass keyboard control to the console. Then switch to console and kill X from there. The SysRq key is sometimes marked PrntScn. You have to  press


This should allow you to switch to the console by pressing


Once on the console, kill the X Server

killall Xorg

Warm Reboot

If that fails, you have to do a warm reboot then fsck. If you have a current distro and ext3 or equivalent filesystem, you should be okay. Press the reset button and wait for the system to reboot.

Check your X log under /var/log/Xorg.0.log to see what caused the lock up.

# less /var/log/Xorg.0.log


Emacs Web Jump

From Here To There

Use Emacs. Can't be bothered to fumble the mouse, launch a browser, enter URL and maybe a search term? Then try Web Jump. Its part of Emacs and works like this:

M-x webjump
WebJump to site: google
Google query: Linux

Emacs fires up Firefox, Google and passes your query to Google ready to for your enjoyment.

You may find it useful.


StumpWM Install

The Right Way

Installed StumpWM last week and have been running it as my Window Manager for a few days. I like it. It's very different to many mainstream Window Managers or Desktop Environments.

StumpWM is keyboard centric. Usable without a mouse. In fact that was the primary design principle. Once StumpWM is running, there is nothing to click. No icons. No buttons. Nothing for the mouse to do.

Documentation is not extensive, and it takes some getting used to keyboard only usage. Once you start to get the feel, its great.

I hit a problem using StumpWm. Sometimes it hangs. Kill Xorg and log back in is the only solution.

StumpWM requires you to install LISP before you install Stump. I installed CLISP - an ANSI Common Lisp Implementation from After the recurring hangs, I searched for a fix and found this:
Multi-threading is available in SBCL, though not in CLISP. Running Swank (or any other command that doesn’t fork or exit) on a single-threaded StumpWM will hang StumpWM. You’ll be able to move the mouse, but the prefix key won’t react anymore. You’ll have to Ctrl+Alt+Backspace to start a new session.
And there's the rub...

I uninstall CLISP and StumpWM and start afresh.

I'm running Debian. Here' s how I did it:

1. Install SBCL

# aptitude install sbcl

2. Install CL-CLX-SBCL. An X11 Common Lisp client library for SBCL

# aptitude install cl-clx-sbcl

3. Install CL-PPCRE. Portable Regular Express Library for Common Lisp 

# aptitude install cl-ppcre

4. Install StumpWM. Common Lisp window manager

# aptitude install stumpwm

Check StumpWM is in the path

# ls /usr/bin/stumpwm

On Debian the default install is under /usr/bin/stumpwm. I have seen references to /usr/local/bin/stumwm on some systems. Check the location to ensure its correct.

Ensure X launches StumpWM by adding a line to .xinitrc

$ echo "exec stumpwm >> ~.xinitrc

Create symlink from .~/xsession to ~/.xinitrc

$ ln -s /home/myname/.xinitrc /home/myname/.xsession

Kill and restart Xorg.

I kept my other Window Manager  in case there were further problems to resolve.

You can add StumpWM as an entry to GDM sessions menu using Emacs or another editor

emacs /usr/share/xsessions/stumpwm.desktop

[Desktop Entry]
Comment=Tiling Window Manager

Save file. Restart X server.

Normally hit Ctrl-Alt-Del to kill and restart X server. If that fails, as root user, open XTerm and do:

# ps -e | grep X
6408 tty8     00:06:43 Xorg

# killall Xorg 

X server will die and restart.


Debian Aptitude Too Big

Getting Fat

Using aptitude since last clean install, I recently observed how big /var had grown. Starting around 100 Megabytes, it now stood at a whopping 2.5 Gigabytes. I suspected it was caused by aptitude's cache archive. Running du -sh /var confirmed it.

Deb files are stored in /var/cache/apt/archives. Aptitude's cache was now 2.3 Gigabytes in size. Time to trim.

I ran aptitude autoclean:

# aptitude autoclean

It took around 1 minute and reduced the cache by 1.4 Gigabytes. Still too much. I ran aptitude clean:

# aptitude clean

This purges pretty much everything. Check again and it was down to a manageable 263 Megabytes. Okay.

Keep an eye on aptitude. Its a disk space hog.


Linux Firewall


If your looking for a free firewall (free as in liberty and in beer), then go check out Firestarter.

Its an Open Source easy to use firewall with GUI setup and admin.

Its simple to use and has many options. It even has Internet Connection Sharing similar to Windows XP.

If you don't feel comfortable reworking those IPTables rules, go download and install Firestarter.

Its great for laptops, desktops or servers.


Fujitsu Amilo Laptop


I bought a Fujitsu Amilo budget notebook for occasional use when away from home. Overall the laptop is pretty good, my only complaint is that battery life is dismal. You get around one hour usage, before it shuts down. Stay close to a power outlet at all times.

It came with Vista Home Edition installed. That was buggy and slow. But that was gone a short while later. Grabbed the Debian Net Install Disk, and completed a laptop install. Now it purrs along.

Its a nice notebook, with decent graphics, a large disk, and plenty of RAM. Three USB ports, inbuilt card reader, wireless and lan connections.

Aside from the poor battery performance, I'm pleased with the machine.

Here's the full specification:

Fujitsu-Siemens Amilo Pi 2515 Notebook specifications

Intel Core 2 Duo T7100 1.8 GHz

Intel GM965

2048 MB, DDR2 PC5300 667MHz. 2x1024MB

Graphics adapter
Intel Graphics Media Accelerator (GMA) X3100, up to 384MB video RAM

15.4 inch 16:10, 1280x800 pixel, WXGA BrightView, TFT

160 GB - 5400 rpm, WD Scorpio WD1600BEVS

Motorola Si3054

1 Express Card 54mm, 3 USB 2.0, 1 VGA, 56k V.92 Modem

Audio Connections
Microphone, Earphones,

Card Reader
4in1 Cardreader

Realtek RTL8101 (10/100MBit),
Intel PRO/Wireless 3945ABG 802.11 a/b/g

Optical drive
Optiarc DVD RW AD-7540A
8x (DVD-R/+R/+R DL/-RW/+RW/-ROM)

length x width x height (mm): 355 x 255 x 40

Weight: 2.71 kg
Power Supply: 0.3 kg

44.4 Wh Lithium-Ion, 11.1V 4000mAh

MPlayer Audio Track

Identify And Select

Using MPlayer on the command line, sometimes a movie defaults to, and plays the wrong audio track. How do you identify the correct track? How do you select the correct audio track?

First check the audio tracks available on your movie. This one is in matroska (mkv) format.

$ mplayer -identify greatmovie.mkv
[matroska,webm @ 0x374eae0] max_analyze_duration reached
[matroska,webm @ 0x374eae0] Estimating duration from bitrate, this may be inaccurate
ID_AID_0_LANG=eng <-- Here's the audio we want!
ID_AID_1_NAME=Commentary actor, director
ID_SID_1_NAME=English (SDH)
ID_VIDEO_ASPECT=2.4242 <-- Here's the aspect ratio!

Now we have the audio track details, we can pass that value to MPlayer when we start the movie:

mplayer -aspect 2.42:1 -aid 0 greatmovie.mkv

MPlayer will now play the audio track we want.


Using Linux Find


Linux find utility is a great tool for digging out files buried in the vast depths of your disk platters. Not quite as good as  Google, but a lot smaller and already built into your Linux OS.

If you have an inkling of your file details, find can locate it. I misplaced some files a couple of months ago. I knew I had worked on them on another machine and was pretty sure, a copy resided on my disk, somewhere.

I found a date reference to the files. It was all I needed. find did the rest.

I knew I had last worked on the files on 19 July. I calculated the number of days, using fingers and toes, and passed the number to 'find'.

It was 137 days since I last modified or accessed the file. Here's the find command.

find . -mtime 137 -print


find - the find command
'.'  - start search in the current directory
-mtime - look at files last modified
137 - days ago
-print - print out results

Minutes later, I had my files.

You can search for files by name, using -name instead of -mtime.

Add wildcards:

find . -name *.gif

Searches for all gif files in current directory and sub-directories.



Convert DVD VOB Video Files To AVI Format

A friend has some home videos as DVD. He wants to convert the DVD files to AVI so he can edit them with a movie editor.

This is how to do it.

N.B. This is for DVD home movies which are NOT encrypted. This will not work for DVD Videos such as those produced by the Hollywood studios. The movie industry has worked to prevent back up copies of DVDs by encrypting content.

This is for the Windows platform. You can achieve the same using Debian/Linux. I'll leave that for another day.

Download and install the following software:

DVDFab HD Decrypter

Avidemux Video Editor


Fireup DVDFab HD Decrypter. Place your DVD video disc in the drive. When it spins up, DVDFab should detect it and start to scan the disc. DVDFab will ask you to specify the region code. Western Europe for us.

The DVD video will be identified in the field at top marked 'Source'. Click field underneath marked 'Target' and select a drive and a folder / directory to output the ripped DVD data. Make a note of the directory/folder the ripped data is in. You will need to know that a little later.

Click start. Go grab a coffee or watch wrestling. When its finished close DVDFab. Its done its work for today.


Fire up Avidemux. We want to convert the file to AVI.

Left hand panel. Click drop down arrow button under Video. Select MPEG-4 ASP (Xvid)
Left hand panel. Click drop down arrow button under Audio. Select MP3 (lame)
Left hand panel. Click drop down arrow button under Format. Select AVI

Click folder on toolbar go to the location where DVDFab put the ripped files. You do remember the folder location, dont you?

Click it and open the folder makred VIDEO_TS.

Ignore .BUP, .IFO, .idx files.

Select the first VOB file. Should be something like VTS_01_0.VOB. Click 'Open'

Avidemux confirms its opened the file.

Back at main screen, click Save. Second button from left on toolbar. Image of floppy disk.

Give the file a name, including '.avi. extionsion. Avidemux will not add the extension for you.

Avidemux starts conversion.

Go grab a coffee or watch some more wrestling. This could take a couple of hours.

For large files, run it over night.



ASCII Character Set

The ASCII character set defines 128 characters.
0 to 127 dec. 0 to FF hex. 0 to 177 oct.

ASCII is an acronym for American Standard Code for Information Interchange.

The standard set consists of 128 decimal numbers from zero to 127. These are  assigned to letters, numbers, punctuation marks, and special characters.

Control Characters

The first 32 values are non-printing control characters, such as Return and Line feed. Generated by pressing Control and another key. Bell is value 7, Control plus G, shown as ^G.

Notice that Bell decimal value is 7. G decimal value is 71. The Control key subtracts 64 from the value of the key it modifies. So Bell is 64 less than the value of G.

ie 71 - 64 = 7

Here's a jpg with 128 ASCII codes, 0 to 127.


GStreamer unable to detect any sound devices

No Sound

GStreamer was unable to detect any sound devices. Some sound system specific GStreamer packages may be missing. It may also be a permissions problem.

The error messageI was getting. I installed a few things for testing. Something broke. I googled for a solution without luck.

XFCE4 mixer was greyed out. I couldn't use it. I could use AlsaMixer. I could get sound using MPlayer. I could get sound using Audacious.

I tried to remove gstreamer using aptitude without luck. As root I deleted gstreamer files and directories:

rm -rf /usr/lib/gstreamer-0.10 

I tried aptitude again:

aptitude remove gstreamer0.10-alsa

This time it worked. I got:

root# aptitude remove gstreamer0.10-alsa
The following packages will be REMOVED:  
0 packages upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 578 kB will be freed.
(Reading database ... 91754 files and directories currently installed.)
Removing gstreamer0.10-alsa ...

I purged gstreamer0.10-alsa and installed it again. It worked. This time audacious didn't complain when I fired it up. XFCE4 mixer was stilled grayed out. I removed it from XFCE4 panel and added a new XFCE4 mixer.