All posts by Chinmoy Kanjilal

Chinmoy Kanjilal is a FOSS enthusiast and evangelist. He is passionate about Android. Security exploits turn him on and he loves to tinker with computer networks. He rants occasionally at Techarraz.com. You can connect with him on Twitter @ckandroid.

CpuLimit : Limit Processsor Usage of Applications

Linux has an option of Frequency Scaling which lets us adjust the maximum CPU usage of the whole system instantaneously. But, sometimes we might like to selectively apply CPU resources and speeds to applications.

Beyond Limits

This is possible on Linux with CPU Limit. CPU Limit lets us limit the CPU usage of a particular application or a process by it’s PID ( Process ID )on a Linux system according to a percentage, the current usage being 100%.

Not only this, CPU Limit can automatically adjust itself according to the overall system load, so we can always use CPU limit safely, without the fear of causing any unbalanced activity.

Currently CPU Limit can only be used from the command line. For a detailed overview on how to use CPU Limit, you can check out this page.

CPU Limit has a minimum system requirement of the Linux Kernel 2.2. One notable fact here is that, if you have multi-CPU system, your maximum CPU frequency limit is not 100 % but n times 100, where n is the number of CPUs. Another limitation is that CPU Limit can only allow you to under-clock a process, but not over-clock it. But still, it is the first application of it’s kind for Linux.

To get CPU Limit, go to the SourceForge page on CPU Limit here : Download CPU Limit

Wine 1.1.29 Released with New Features

Wine 1.1.29 is out and it has brought a huge load of new features along with it. For those who are not too sure about what Wine is, I recommend you read this first : Wine – What you need to know. For those who do not wish to read it, Wine is an application which lets you run the windows API libraries on Linux, basically allowing most general purpose Windows applications to run inside of Linux in the Wine environment.

Wine recently got it’s new development release out. With Wine 1.1.29, we have:

  • Improved Gecko integration, by using  Wine’s network layers.
  • Use of external libmpg123 for mp3 decoding.
  • Better handling of Internet proxy settings.
  • Better support for jpeg and png formats.
  • Fixes on some game installers not working with Wine.
  • Fixes on the UI, showing wrong buttons and poor layout at places.
  • Fixed 64 bit Wine installer.

With all these fixes and improvements, Wine is surely on a define path to improvement. This brings good news to many other projects which are completely built on Wine, like Cedega from Trans Gaming which although commercial, uses Wine for it’s base to run windows games on Linux with full graphics support.

DigiKam : Photo manager for KDE

I am not much of a KDE user but sometimes the features on offer from a KDE application are much more appealing than Gnome. One such application I recently came accross is DigiKam. DigiKam is a complete image editor, manager and one of the really good image organizers for Linux, besides Picasa.

With DigiKam, you can easily sort and search through images. DigiKam can organize your images based on tag, category, search result, date and time and a timeline. That makes it a complete photo manager.

Digikam
Digikam

DigiKam has the options of using ratings for individual images as well as to albums. The plugin support extends the use of DigiKam from the desktop to the web. There are numerous plugins to add support for Facebook ,Flickr, Google Earth and for creating web-albums. You also have the option to create easy web-galleries.

DigiKam also supports on the fly editing to images when they are being transferred to the computer from the Digicam.

The image editing features offered by DigiKam are red eye removal, color adjustment and various image effects. The newer version has support for GPS Locator, Metadata editor and iPod Photo Uploader.

The application is written in C++ and uses the QT frontend. It is also planning to use MySQL for the database which will allow the database to be shares and synchronized across a network. The development team behind DigiKam is quite responsive.

You can try DigiKam here: Get DigiKam [ approx. 13.5 MB ]

DigiKam is also available as a windows software: Get DigiKam for Windows

Font Matrix : Manage Fonts on Ubuntu Linux

Installing Fonts on Ubuntu has been covered earlier in the post titled How to install fonts on Ubuntu. But, a font manager along with this would go a step further to a better UI on Ubuntu Linux. A font manager lets us group fonts, tag them and put them under categories else that simply viewing them.

Font Manager
Font Manager

Font Matrix is a cool application with which we can easily manage fonts on a Ubuntu system.

The Font management can be done for the complete system as a root user as well as for individual user accounts. Font Matrix uses the freetype engine to render fonts and the QT framework to provide the frontend for the application which is quite user friendly and well built as is evident from the screenshot.

Another great feature of Font Matrix is labeling of fonts, and tagging them which makes it a font manager and not just a simple font viewer.

With no built in application for managing, labeling and tagging fonts in Ubuntu, font manager equals it’s windows counterparts to a good extent and is a must have application for Ubuntu Linux.

To download Font Matrix for any Debian based system, visit the download page here : Font Matrix Download

How to Enable Font Smoothing in Wine

I had covered Font Smoothing in Ubuntu, in one of my previous posts.

A good font display is a top priority for me because without good fonts, any application howsoever good it might be looks like a sloppy Sunday night’s work.

Now, getting font smoothing on Ubuntu is easy. It involves editing a file to enable autohint but these smoothings are not applicable to Wine. On top of that, most of the times, the fonts of Windows  applications running in Wine are highly aliased and appear broken, sometimes illegible. This can be corrected with applying font smoothing inside Wine.

To do this, there are many tutorials which require you to create a registry key inside wine and do heavy tweaking. To keep things simple, there is an easy way out. Follow the tutorial here.

Wine Fonts
Wine Font Smoothing

[ Screenshot from Ubuntu Forums ]

This tutorial includes downloading a simple bash script, and installing it, in two easy steps through the command line. Your font rendering in Wine should improve considerably after this tweak.

Avant Window Navigator : Must Have Linux Software

Ubuntu Linux has many eye candy softwares but all the dock applications available for Ubuntu do not match their counterparts in Windows. But, there is one dock application which works as smoothly as the compiz desktop effects and with perfectly smooth transitions as well. This software is available across many Linux distros.

Avant Window Navigator
Avant Window Navigator

With Avant Window Navigator, you can dock window lists, launcher and third party applications in the AWN dock which rests at the bottom of your desktop primarily.

As a windows list, it stacks up similar applications into the same icon, as an application launcher, it can let you launch applications, maximize, minimize with single clicks as if it were just another Window. You can also set the visibility of these windows to hidden of always on top. That way, it forms a complete replacement for the bottom panel in Ubuntu Linux.

This application requires a composition manager like Beryl or Compiz to function properly. It is also available for the Xcfe desktop environment.

You can also drag and drop applications on applications in the dock to perform an “Open with” operation. It has an excellent glass engine on the background. Written in C, AWN uses the GTK+ frontend to deliver sleek graphics and transition effects.

Currently AWN is available for Gentoo, Ubuntu, Fedora and for OpenSuse.

To install AWN on your Linux distro, go to the installation page here .

Slackware 13.0 Released with Official 64 bit Port

Slackware is one Linux distro which has not gotten distracted with all the eye candy flying around on  Linux distros and has always tried to keep things simple and serious.

Slackware
Slackware

This is precisely the reason Slackware is used for distros like Backtrack, which is a powerful security scanner tool set available as The Backtrack Linux Distro. Very recently, Slackware has released its version 13.0 which includes an improved collection of the X packages.

But the biggest change in the latest version is a new feature: 64 bit support. This ensures  an ongoing development for 32 bit with a net port to the 64 bit, being managed alongside. There are changes in wicd, and new Intel drivers have also been included in this latest release.

A new Intel driver is experimental and is not present at the regular location. Other advancements include an improved KDE version 4.2.4 which is the latest stable version and Xcfe environment and a new package format, the .txz format with a higher compression that the regular .tz format. Apart from KDE and Xcfe, Gnome desktop is also available for Slackware.

This new version of Slackware requires the latest build of the Linux Kernel, version 2.6.22.xx is the minimum requirement.

Get your copy of the latest release here .

How to use a Ramdisk in Linux

Ramdisk is a feature in Linux which lets us use a RAM device as if it were a storage media. A RAM disk has a fixed size and behaves like just another disk partition with exceptionally fast speed. As the disk is physically located on the RAM, it’s access time is as fast as that of the RAM.

With a RAM disk, we can keep temporary data needing fast calculations and access in the RAM. This may include caches, compressed files and encrypted files. Using the RAM disk as a web cache can speed up browsing considerably. It can also be used to load guest operating systems for faster virtualization.

The only disadvantage of using a RAM disk is that you will lose all data in case of a power failure. But, this comes as an advantage in case when you are browsing through the Internet and using the RAM disk to store the cache or when you are using RAM disk to deal with encrypted files. In both the cases, the data is lost without a trace and desirably.

Support for creating RAM disks has been present in Linux from the Kernel Version 2.4.

To create and use a RAM disk, you can see the step by step guide to creating a RAM disk .

This tutorial is for Red Hat which has a number of built in RAM disks. For other distros of Linux, based on the kernel 2.4 and above, the tutorial should work equally fine.

How to add Google Repositories to Ubuntu Linux

Google releases regular updates for it’s Linux distributions of Picasa and Google Desktop applications. Picasa is an amazing image viewer and manager. It is one of my most used softwares for Linux when it comes to viewing image albums.

Default update service for Picasa is not present in Ubuntu itself, but can be easily added. Now, this can be done with a GUI as well as from the command line.

To add Google repositories from the command line, follow the steps below.

  1. Add the GPG signing key for Google repositories by entering
    wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -
    apt-get update

    into your terminal.

  2. To add the repository URL, open the file /etc/apt/sources.list and append the following code at the end
    # Google software repository
    deb http://dl.google.com/linux/deb/
    stable non-free main
  3. Update your software package update list with
    sudo apt-get update
  4. Update Picasa with
     sudo apt-get install picasa

Now, your Picasa will update automatically with your other packages every time Google provides an update. This will also fetch package update lists for any other Google software you use.

How to Get Smooth Fonts in Ubuntu

Fonts is an area which needs a lot of improvement in Linux. With the lack of good fonts, Linux applications and softwares always lack that smooth looking competition from the Windows GUI. Most of the fonts available by default on Ubuntu are just barely enough to work with and the others which we can install manually, lack the crisp and sharp font effect we get on windows.

Ubuntu
Ubuntu

I had covered installing fonts on Linux earlier. Now,  you might also like to add font smoothing to the fonts you install. This will improve the visual aspects of your Ubuntu installations remarkably.

To enable font smoothing for true type fonts,

  1. Go to your home directory.
  2. Press ctrl+h. This will enable showing hidden files.
  3. Lookup the  .fonts.conf file.
  4. Edit the file to make it look like this
  5. <?xml version="1.0"?>
    <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
    <fontconfig>
    <match target="font">
    <edit name="autohint" mode="assign">
    <bool>true</bool>
    </edit>
    </match>
    </fontconfig>

That is all. Now logout and log back in. Your font should be smoother than before. To test this check the font rendering of a white text against a black background.

For more details, see original Ubuntu forums discussions here.

Get Opera 10 For Ubuntu [Linux]

Ubuntu comes bundled with Firefox as the default web browser. Firefox, with all it’s addons and customizations, is a great browser in itself, but it’s toll on the memory is a big annoyance at times. For those suffering from this, you can try out the Opera web browser for Ubuntu.

Opera 10
Opera 10

Opera has always been an innovative web browser and has a rapid growth in the browser sector. It has in built support for many of the features offered by many Firefox plugins. Opera has an extremely smooth tab switching and has introduced a revolutionary feature of Opera Turbo in it’s version 10, which is an unmatched integrated-into-browser technology to speed up web browsing.

Today, Opera has unveiled the final build of version 10 of it’s web browser and it is available both for windows as well as for Linux.

Opera 10 has some new features, like visual tabs showing a page preview on the tab, automatic memory management depending on system resources and a lot more. You can get a detailed overview of these features at Pallab’s blog post on Opera 10-new features.

Currently, Opera 10 is available as a package for all major Linux versions like Ubuntu, Mandriva, Slackware, Suse, Mint, Fedora, Gento etc.

To get the Opera 10 package for Ubuntu or for any Linux platform, visit the Opera 10 download page for Linux .

GParted : Must have Linux Software

GParted

Windows has many limitations on the number and types of partitions we can create. Also, it becomes very hard to edit or modify the system partition in Windows. There are third party softwares like Norton Partition Magic which let us do just that but they come for a price, and are not very user friendly.

GParted is a Linux software which lets us manage our partitions, all for free. GParted is written completely in the C++ language and is pretty lightweight as it uses GTK+ frontend. It can detect, read and create all major file system. GParted can run at the boot level. This gives it unrestricted access to all partitions. Some of the features of GParted are:

  • It can Create or delete partitions. With GParted, we can also set partition types while creating partitions and bypass the windows limit on the number and types of partitions.
  • GParted also lets us resize and move partitions. This helps us rearrange data.
  • We also have options of copying and pasting full partitions.

But these are not the only reasons to use GParted. GParted is available along with many Linux distributions as well as a standalone Live CD which can be downloaded here: Download GParted Live CD

Backtrack : Linux Distro for the White Hat

Backtrack is a slackware based Linux distro which uses the KDE environment. Backtrack was developed by the Mati Aharoni, an Israeli security consultant.

BacktrackThis distro helps in extensive testings of workstations for security loopholes on both the system itself as well as on a network.

Today, from being a simple Slackware based distro, it is a complete security analysis tool used by professionals all over the world. Backtrack has taken computer security to such a level, that now we have a new field of education called “Offensive Security” with a certification, the education for which is focused around the use of this distro.

With a variety of spoofing tools, sniffers, tunneling softwares and much more, Backtrack is the perfect choice for any hacker or anyone interested in learning network exploits and ways to prevent them. It has more than 300 tools arranged categorically, and was awarded the #1 Security Live Distribution. It includes popular applications like Wireshark, chntpw etc. chntpw can be used to reset a lost password for windows. Other tools are also available for fun on computer networks.

Backtrack can be downloaded for free. The Version 3 is 700 MB in size, whereas the version 4 which is a pre-final version currently is 1.32 GB in size.

Get backtrack here.

Clonezilla : Partition Snapshot Software

Clonezilla is a software which lets us create clone images of partitions. The software is actually a Debian based bootable Linux with support for cloning partitions and disks. It includes the ntfsclone, partclone and partimage softwares along with the bootable live distro.

Clonezilla
The technology on which Clonezilla is based is the same as the proprietary software Norton Ghost, or it’s open source counterpart Partition Image. But the difference here is that Clonezilla is a thousand times faster than these softwares. It is said that the Server edition of Clonezilla can clone around 5 GB of data to more than 40 computers in less than 10 minutes. That is faster than any other disk cloning software. This technology of cloning through a server is called Multicasting Cloning. Clonezilla also supports Unicasting Cloning, whereby we can clone a single computer to another single one.

Currently, Clonezilla supports over 10 file systems including ext2, ext3, ext4, xfs etc of Linux, NTFS and FAT of Windows and HFS+ of Mac OS.

This software will come in very handy if you are running a web server and want to clone-backup it. Alternatively, we can also setup a cronjob to schedule this backup. clonezilla is licensed under GPL, which means all this, can be done for free.

to download Clonezilla, go to the download page here.

Launchy : Must have Ubuntu Software

Launchy is a revolutionary open source application available for both Linux and Windows. It is a real time keystroke launcher for searching through installed programs and system paths for executables specific to the system and run them.
Launchy

Launchy maintains a small index of it’s own and we can check the number of files in the index. The index is updated automatically on schedule but there are options for manual updates as well.

Originally suggested as a Windows start menu replacement, it has a search algorithm which surpasses the search algorithm of the Windows start menu launchy.

With Launchy, we can search both the web as well as our desktop. Another popular feature in Launchy is a real time calculator. So we just go on typing an expression and it evaluates in real time. Parenthesizing expressions is also allowed. In addition to this, Launchy has extensive suppport for themes and plugins.
The application takes a very small amount of memory and is a must have software for both Windows and Linux.

Get Launchy here.