Inspirated

Threads are love. Threads are speed. And more often than not, threads are a consistent PITA. However, I’ve had an accidental epiphany just a few hours ago:

“When in doubt When you need to communicate among threads, use synchronized Queues.”

There. This magic mantra will solve more issues in your life than you can ever imagine, and certainly more than I expected.

Getting back to the topic at hand, adding threading support to the program has sped up the bookmark checking process by a factor of about 435895234. Coupled with fixing of some parsing bugs, Bookmark Undertaker v0.3 is finally capable of providing a quick, stable and consistent way of sanitizing your Firefox favorites:

This time, I’ve also tried to provide Deb and RPM packages on the release page for easy installation by the Debian/Ubuntu/Fedora populace.

Ushering in the era of communist applications:

“If everyone gives one thread, the poor person will have a shirt.” — Russian Proverb

While developing PyS60 apps is one of the most fun things you could do with your Nokia phone, debugging them isn’t as zippy as one would hope for in a Py development environment. To make up for that, PyS60 gives the developers an option for directly connecting to the interpreter through Bluetooth. Doesn’t sound very appealing? How about this: You connect your laptop with the cellphone, jump in at some place in the code while your app is executing and then use lappy’s big keyboard for exploiting different code and values in the interpreter. Sounds better?

To accomplish this on a Linux distro, you will need the following packages installed on your system:

After making sure that both are present on your system, install PyS60 on your phone if you haven’t already done so.

Now the fun part:

1. Switch on Bluetooth in the cellphone.

   

2. Launch bluetooth-properties and click on “Setup New Device”.

   

3. Select your cellphone.

   

4. You will be shown a pin.

   

5. Enter the pin when queried on the cellphone.

   

6. The phone should be successfully paired.

   

7. Authorize your Linux system to make automatic connections to the phone.

   

8. As root, run this shell script:

   [root@orthanc ~]# ./rfcomm-listen.sh

   Serial Port service registered
   Waiting for connection on channel 2

9. Launch PyS60 interpreter and select “Bluetooth Console” from the application menu.

   

10. Select your Linux machine.

    

    The command you ran in previous step should have new output:

    [root@orthanc ~]# ./rfcomm-listen.sh

    Serial Port service registered
    Waiting for connection on channel 2
    Connection from 00:17:4B:B6:35:31 to /dev/rfcomm0
    Press CTRL-C for hangup

    The cellphone screen should be showing something like this:

    

11. As root again, open a new terminal and run:

    [root@orthanc ~]# cu -l /dev/rfcomm0

    Connected.

12. Hit Enter till prompt (>>>) appears, then type:
    

    >>> import appuifw
    >>> appuifw.query(u'Hello World', 'text')

13. Viola, you should have an input box on the mobile screen:

    

14. Enter any text and press the OK key. It should be show up in the terminal you were using to type in code:
    

    >>> import appuifw
    >>> appuifw.query(u'Hello World', 'text')
    u’Finally’

15. Exit the interpreter by typing CTRL+D on an empty line:
    

    >>> import appuifw
    >>> appuifw.query(u'Hello World', 'text')
    u’Finally’
    >>>
    Interactive interpreter finished.
    cu: Got hangup signal

    Disconnected.

Pat yourself on the back. Now, you can use your Bluetooth console to import your modules, execute some stuff and then jump in the middle to test some extra lines or values. In fact, I found it to be a pretty darned good way of learning about PyS60’s API. Res secundae!

Going through the Planet Fedora feed, I spotted this excellent write-up which tries to explain Fedora-related patent questions such as “why the $*#@ won’t Red Hat give us MP3 playback support“. I would be straight-down lying if I said that the article offered nothing new to me. In fact, some answers, such as this one … :

Patent licenses are usually granted via payment of royalty based on the number of users. Since Fedora is free and open source software, the effective number of users is essentially unrestricted. Patent holders are generally unwilling to give a blanket patent license for unlimited use, and the royalty payments for these licenses would be too high to purchase them outright. Proprietary operating systems like Microsoft Windows include the cost of the patent license as part of the product being sold to the end users. Fedora is not sold commercially, so there is no way to recoup these substantial expenses. Even assuming funds are available to do so, licenses such as the GPL require a written patent grant (in regions where software patents are enforced) compatible with royalty free distribution and modification. Since meeting this requirement effectively nullifies the effect of a patent, patent holders are also generally unwilling to do this.

… clarified in my mind a few long-held confusions about Fedora’s reluctance regarding patent infringement. For the general user, RPM Fusion works around all that crap; but a read of the linked FAQ is recommended nevertheless for having an idea about the issues inherently involved with seemingly simple tasks such as playing DVDs.

There is a reason why I never evangelize Fedora much: it’s far from perfect. There is also a reason why I use Fedora for my everyday Linux-ing: it’s good when it starts working. The two seemingly conflicting viewpoints are not mutually exclusive, since Fedora’s instability as well as its appeal can be termed in one word: bleeding-edge.

The biannual cycle of backup-reinstall-reconfigure for each new Fedora release works fine for me. It takes a day or two to get everything back to the way want them to be, but the trade-off is almost always worth it. Consider this, upgrading from a Fedora version to the next will almost never work seamlessly. Nevertheless, the re-installation mantra allowed me to use PulseAudio’s “perfect” setup much before most of the other distros’ users. The fact that I got a clean start for the new sound architecture also explains why I never had any incompatibility issues with it and consequently, my status as one of its huge fans.

Another reason why I’m still hanging on to Fedora is because of the familiarity factor, as I no longer have the ample time for trying out newer distributions just for the sake of it. Linux From Scratch was a mighty fun experience, but keeping it up-to-date was nothing short of a Herculean task. Gentoo sounds very appealing, but I don’t want to download a DVD, go through the hassle of installing and getting familiar with the new distro and then emerge a whole universe of updates on an internet connection as reliable as Fedora on Hurd. The perfect solution would be to install a new release of Gentoo but unfortunately, it’s been over an year now since I started waiting for one.

Which brings us to Fedora 11 — lovingly nicknamed after everyone’s favorite Spartan king.

The predominant aspects of the new release which affect me as a user are the Ext4 filesystem and the Kernel Modesetting feature. So far, I am not even using the former. Yes, yes, I know I bragged about bleeding-edge before, but let me explain why I did not go for it in this particular case:

• Filesystem is the most critical aspect of a system for me. I can toy around and experiment with everything but this holy grail. If my audio fails, I can try fixing it. If X stops working, ditto. If my data is corrupted, I’m FUBAR.
• Anaconda crashed when I tried to update the boot-loader configuration for a system with Ext4 partitions.
• I couldn’t find a way to use Ext4 without using the Logical Volume Manager. I like my partitions as /dev/sdaX and entries such as /dev/mapper/yourmom/blahblahblah/finallythedrive in the fstab file turn me off.

Nevertheless, KMS made up for the Ext4 — or lack thereof.

• Booting is now prettier.
• Working in runlevel 3 is so much more efficient because of all the extra space provided by higher resolution.
• Switching virtual terminals and X sessions is a breeze.
• Suspend/Resume is a bit more stable.

Other significant changes include Xfce 4.6, Firefox 3.5 and the reworked volume management in Pulse. Overall, I’m pretty satisfied with my decision to upgrade, and here’s to the hoping that the next 6 months will go as smooth as the previous ones.

The 100th post, and considering that the most popular ones on the blog so far have been screencasts, there wouldn’t have been a better way to commemorate the occasion than editing a short music-video which would demonstrate the prowess of Linux on desktop.

Every once a while, I need to take the backup of my Nokia N72 using PC Suite. Since the task had to be performed on Windows, I expected my virtualized machine to be able to do so. Unfortunately, Virtual Machine Manager does not provide any option in its interface which would allow me to use my USB devices in virtualized machines. Going through the documentation though, here’s the method through which I was able to solve my issue.

First of all, you should have the vendor and product ID’s of the USB device you want to use. Sounds alien? Use the command:

[user@host ~]$ lsusb

Which will show you something like:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 002: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 003: ID 0421:04c4 Nokia Mobile Phones
Bus 003 Device 002: ID 09da:000a A4 Tech Co., Ltd Port Mouse
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

The bold numbers in the line containing “Nokia Mobile Phones” are the vendor and product IDs respectively. Once you’ve noted them down for your required device (in my case: 0x421 and 0x4c4), list the virtual machines’ configuration files:

[user@host ~]$ sudo ls /etc/libvirt/qemu

networks windoze.xml

My virtual machine was named “windoze”, so windoze.xml is the file that I need to edit:

[user@host ~]$ sudo gedit /etc/libvirt/qemu/windoze.xml

In the editor, add the highlighted hostdev lines under the devices section (replacing the vendor and product IDs with the ones noted down from lsusb output):

<devices>
<emulator>/usr/bin/qemu-kvm</emulator>
<hostdev mode='subsystem' type='usb'>
<source>
<vendor id='0x0421' />
<product id='0x04c4' />
</source>
</hostdev>

Save and close the file. Restart the service:

[user@host ~]$ sudo service libvirtd restart

If everything went smoothly, the USB device should now be accessible from within the virtual machine:

(Click on the thumbnail for larger version.)

(Or: Using Wine where plain-water should have been more than enough.)

Packet Tracer is a network simulator for Cisco devices. Caveat: It runs only on Windoze. Hence, there are three possible solutions for someone in need of using Cisco simulation on Linux:

• Wine: Wine’s setup varies from distribution to distribution. If you’re using Ubuntu, following commands should do the trick:

  [user@host ~]$ sudo apt-get install wine
  [user@host ~]$ winecfg

  Alternatively, for Fedora/RHEL/CentOS, use:

  [user@host ~]$ sudo yum install wine
  [user@host ~]$ winecfg

  Followed by:

  [user@host ~]$ wine /path/to/PacketTracerSetup.exe

  Once installed, you end up with:

  
  (Click on the thumbnail for larger version.)

  Pretty much usable. Although, fonts appear hideously ugly on default settings. Fortunately, you can change their sizes by going to Options >> Preferences >> Fonts from the Main Menu.

• GNS3: Setting up this particular piece of software is considerably difficult and definitely an overkill for newbies. This blog attempts to bridge the difficulty by providing video tutorials for installation, but that does not make GNS3 any lesser intimidating for users not already familiar with Cisco terminology or network simulation. For example, you’ll have to scavenge the Internet for IOS images you want to use, something you’d never have to think about in Packet Tracer for its supported devices.
• Pursue Cisco to release Packet Tracer on Linux: I was a bit surprised when I spotted that Packet Tracer is actually based on the cross-platform Qt GUI toolkit which would make porting it to Linux a trivial task for developers. Regrettably, knocking some sense in Cisco execs’ head is likely to be a far more laborious task than either of the solutions before.

“Sparrows who emulate peacocks are likely to break a thigh.” — Burmese Proverb Some geek Buddha annoyed at the trend of software developers relying on emulation for portability

Update: Cisco had after all started providing a native Linux version of Packet Tracer since last summer which I somehow missed because of its lack of appearances in my initial Google search. Here are the download links:

Fedora RPM: Rapidshare Part 1, Rapidshare Part 2
Debian/Ubuntu Installer: Rapidshare Part 1, Rapidshare Part 2
Linux Addons: Rapidshare

“Evolution is God’s way of issuing upgrades.”

It’s a wonderful age to live in as an open-source enthusiast. The warm feeling is especially accentuated in one’s mind after recalling countless hours of hair-pulling trying to make that goddamned VGA monitor work with Red Hat Linux 6. Software for GNU/Linux has improved at an exponential rate. There are still plenty which lack the user-friendliness and all, but technologically the overall rate of improvement has been nothing short of astounding.

Ask any newcomer to the GNU/Linux world about their favorite open-source projects, and there’s a strong likelihood that the answer will be one of the “prominent big-guns”; the likes of Compiz Fusion, Firefox, KDE or Gnome. Ask any veteran the same question and you’re much more likely to get a diverse stock of answers ranging from Vim to Anjuta or probably even some obscure Window Manager like Fluxbox. The opinion about the most “improved” projects would thus be highly polarizing. Still and all, there are few projects which have eased my life substantially with their progress. To compliment the ones that have almost made me kiss virtual bits of code at one point or other, I’ve decided to choose the top five:

5. recordMyDesktop
   The Dark Ages: Recording a video of an X session was nothing less than a nightmare. With sound, all the more so. The popular method was to run a VNC server and then use a tool such as vnc2swf to capture the footage.
   The Messiah: Once you install recordMyDesktop and one of its GUI frontends, recording becomes as easy as launching it and selecting “Record”. Really, you don’t have to use multiple software now for doing something as simple as that.

4. NetworkManager
   The Dark Ages: You went to your workplace, geared up your Linux distribution and tried get some connectivity and to your utter horror, the Wireless network used WPA encryption for passphrase. wpa_supplicant was the command-line utility you could’ve used for connecting to such networks after hours of tinkering around, but it sadly wouldn’t have prevented you from getting fired because the execs weren’t that much amicable with open-source evangelism in the first place.
   The Messiah: Red Hat, for all the criticisms it receives for RHEL, is still the caring patron figure for desperate Linux users crying out for help. Hence, it’s no co-incidence that this project as well as next two on the list were initiated by the same company. NetworkManager makes mobile connectivity as peachy as it could’ve been. You spend a few days with NM on your notebook and it starts choosing the best network for you wherever you go, that too with least possible intrusion in your workflow.

3. SELinux Troubleshooter
   The Dark Ages: In this particular case, the dark ages don’t belong to that much a distant past since the cause of all the mess was also a recent innovation. Security Enhanced Linux, while obstinately preached by Red Hat and enabled by default on its shipped operating systems, was unanimously loathed by all system administrators who had at one point or other given up their hopes and had disabled it completely on their networks. The error messages it churned out on regular bases were not only cryptic, but also critically hampered regular everyday usage of their host operating systems.
   The Messiah: With improved default policies, the situation was somewhat resolved for general user. Nevertheless, irregularities still kept popping up occasionally and hence came SELinux Troubleshooter to the rescue. For every cryptic denial that SELinux now pops up, the Troubleshooter will analyze it and even suggest workarounds for them so that you don’t have to manually mess with policy modules every time something perfectly legitimate starts getting labeled as “unauthorized” access.

2. PulseAudio
   The Dark Ages: The music player was playing a song and you tried having a voice-call or playing another video = epic fail. The audio device was usable by only one application at a time. In fact, sound was the Achilles’ heel for default setups of pretty much every Linux distribution that existed.
   The Messiah: Playing a soundtrack in one application with volume tuned to max and having a video run in another with volume at half is no longer a fantasy. And no, ESD doesn’t even come close to PulseAudio in “seamless” multiplexing of such sounds. If you want more, Pulse can combine multiple soundcards into one and also — hold your breath — redirect audio streams to different hardware on the fly.

1. TrueCrypt
   The Dark Ages: Disk encryption had been an ultra-geek thing for quite a while, especially on Linux. Software that provided such features needed to have modules compiled manually and loaded into the running kernel which opened up a whole plethora of compatibility issues which almost always made newcomers decide against the whole idea per se.
   The Messiah: God bless the developer who had the idea of using FUSE in TrueCrypt for mounting encrypted containers. As a consequence, once a user has installed TrueCrypt, the whole thing doesn’t need to be recompiled again from time to time with updated kernels. Also, thanks to wxWidgets, the GUI has drastically improved too; making it easier for even Linux newbies to utilize disk encryption.

Fortunately, unlike commercial operating systems, GNU/Linux users don’t have to wait for decades before seeing actual new “innovations” in action. Who knows, maybe next year we’ll have LOLPython topping my list. Anything’s probable.

While going through the list of mentoring organizations last night, I realized that there was another software present in them which was dearly loved and efficiently understood by me at the same time. Yup, it’s my favorite distribution — Fedora. I’ve just submitted my application for creating an online reference manual browser which would be able to display info/man pages in hierarchical order of Fedora releases as well as allow its users to perform boolean searches in particular fields. (more…)