Showing posts with label debian. Show all posts
Showing posts with label debian. Show all posts

2012-12-27

Return to blogging!

After several months of silence, here I return to blogging! A few quick updates are in order, in no particular order.

Trivia

  • When the battery of my MacBook Pro began failing in May, I purchased a relatively low-end HP Pavilion dv6 7040TX pre-installed with Windows 7. I mostly like it. It generates very little heat. By contrast, the MacBook Pro is a mini heater for the winter. Another noticeable feature is battery life: I am getting about five hours of development time per charge. The only downside is the low screen resolution, which is 1366x768. In practice, though, it has proved to be adequate for my development needs.
  • It was a rare occasion when I surprised myself by impulsively upgrading the HP computer to Windows 8! My unfamiliarity with Windows was amply proved by the numerous devices and driver difficulties I encountered upon upgrading. Reading a related Microsoft Knowledge Base article revealed that there was an important step that I missed. [For the curious, we are supposed to uninstall and re-install the devices when upgrading in-place.]
  • VMware Player now offers OpenGL-based 3D support for Linux guests. Upon upgrading to the new version of Player, I realised promptly that Debian Wheezy had a problem that prevented it from recognising and utilising 3D devices. It appears as if Sid has this problem as well, since my experimental Aptosid image failed to turn on desktop effects.
  • Thus, I now run Linux Mint 14 KDE. [Of course, it is KDE!] It has been quite stable for my daily development needs (several Emacs windows, Eclipse 3.7 and several Konsole windows and tabs). This is in stark contrast to the frustrating experience with the Cinnamon version, which I downloaded first, mistaking it to be the KDE version. This demonstrates — yet again — why choice is so important, and why it underlies the philosophy of free and open source software!

Largely distracted months

I went through several months of non-work distractions. I am glad that those are nearing their respective conclusions. Not being able to concentrate on work can be really frustrating. More so if one's To Do list is long.

Experiments with languages

During these largely unproductive months, I studied a few languages, peripherally. Here is a summary.

Haskell

I had briefly looked at Haskell, in 2000. It looked so different, I promptly left it. Having gained a little more of functional thinking in the meantime, I decided to take another look at it. A good motivation was Hughes' influential paper "Why Functional Programming Matters". Some Haskell features are straight-forward: type classes, pattern matching, guards in functions, list comprehensions, etc. Some others are deep: higher-order functions, currying, lazy evaluation, etc. A few others go even deeper: functors, applicatives, monads, etc. Haskell demands considerable time and effort — not only the language proper, but the tool chain too. The syntax is layout-sensitive, and I could not even find a decent major mode for Emacs. The package tool called cabal repeatedly left my Haskell environment in an unstable state. Tooling is certainly a problem for the beginner, but otherwise, Haskell is a profound language that makes your thinking better!

Dart

Dart is a curious mix of the semantics of Smalltalk, the syntax of Java and JavaScript, and memory-isolated threads that communicate by sending messages. Added into this curious mix is a compile-time type system that does not affect the run-time object types! Mind you, Dart is strongly-typed. Even though there is a compile-time type system, it is optional and is primarily intended for better tooling, and the language itself is dynamically-typed. The types are carried by the objects, but the variables themselves are untyped. Dart's biggest promise is the ability to write scalable Web applications using a single language on both the server side and the client. The server side seems to present no problems, but the Web programming community is divided in its opinion on Dart's client side promise. The contention arises because Dart has its own virtual machine. Using the VM requires the user to install it as a plug-in in her browser. For those who do not want to use the VM, Dart comes with a cross-compiler that outputs equivalent JavaScript code.

D

I had known of the existence of D for several years, even through I never looked at it in detail. Reading a little about the history of D, I realised that it underwent a rather tumultuous adolescence. With D2, it appears to have entered adulthood. The motivation to look at D was an MSDN Channel 9 video of a presentation by Andre Alexandrescu. D was designed to be a better C++. Several of the design decisions behind it can be better appreciated if we hold that premise in mind. It has a simplified, more uniform syntax, garbage collection, a decent standard library and easier generics. It maintains the ability to directly call a C function in an external library, immediately making a vast set of C libraries accessible. Scoped errors and compile-time function evaluation are examples of D's interesting features. Another notable feature is the partitioning of the language features into safe, trusted and unsafe subsets, with the ability to verify that a module is completely safe, etc. D has good performance that is reasonable compared to that of C++.

Others

I also looked briefly at Erlang and Clojure. However, I did not spend enough time on them to be able to form an opinion.

2012-03-20

Linux distribution chosen!

I had promised to post an update towards the end of January. I did not. However, even the casual reader may have noticed my recent posts related to Debian Wheezy. Those must have served as hints. So, Debian Wheezy it is! I have finally settled on Debian Wheezy with KDE.

Perhaps apt's mechanisms suit my thinking. yum is very powerful, yet the rpm family could not win me over. In fact, at one point, I went close to going back to Arch Linux. However, it is often too cutting-edge — even for a development system.

At the same time, GUI played a non-trivial role in my decision. It also explains why Ubuntu – with its Unity desktop – did not survive in my computer. I felt GNOME to be too restrictive. Some people think that KDE has too many knobs and switches; that it is daunting. Again, perhaps its mechanisms suit my thinking.

With the decision made, I have removed the ISO files of well over a dozen distributions and the VMware images of about half-a-dozen. Peace!

2012-03-17

Debian Wheezy : updating Java alternatives

Debian Wheezy (or even Sid) defaults to Java 6. Originally, my computer had openjdk-6-jdk. I wanted to utilise the newer features in Java 7 such as higher performance and lower memory footprint, and try the Fork-Join framework. Accordingly, I installed openjdk-7-jdk. It updated the Debian alternatives for Java to point to the newer version. So far, so good!

Dependencies can upset the apple cart

Then, I installed Eclipse using apt-get. The version of Eclipse installed is 3.7.1, which is fine. However, it pulls in Java 6 as a dependency. I somehow did not pay attention to that. As the installation completed, I noticed several messages informing me that the alternatives for Java were being reset to Java 6. I bit my lip hard! I think that apt-get should explicitly warn the user if an installation downgrades a package, or more, due to dependencies.

Simple remedy

Fortunately, a simple remedy is possible. But before we begin, we should check the priorities with which both versions are installed. To check the same, issue the following command in a terminal.

> update-alternatives --display javac


javac - auto mode
  link currently points to /usr/lib/jvm/java-6-openjdk-amd64/bin/javac
/usr/lib/jvm/java-6-openjdk-amd64/bin/javac - priority 1061
  slave javac.1.gz: /usr/lib/jvm/java-6-openjdk-amd64/man/man1/javac.1.gz
/usr/lib/jvm/java-7-openjdk-amd64/bin/javac - priority 100
Current 'best' version is '/usr/lib/jvm/java-6-openjdk-amd64/bin/javac'.

Please note the numbers at the end of the full paths of javac. So, both Java 6 and Java 7 are installed, but Java 6 has a higher priority — 1061 to 100. It is, therefore, considered the best version. We can check where /etc/alternatives/javac points, too, for confirmation.

The remedy to apply itself utilises update-alternatives. In order to take care of all the important JDK components in one shot, I collected the commands into a shell script.

> cat up-java-alt.sh

#!/usr/bin/env sh
#
# Update Debian alternatives for Java.

update-alternatives --install \
        /usr/bin/java java \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/java 1100

update-alternatives --install \
        /usr/bin/appletviewer appletviewer \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/appletviewer 1100

update-alternatives --install \
        /usr/bin/apt apt \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/apt 1100

update-alternatives --install \
        /usr/bin/extcheck extcheck \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/extcheck 1100

update-alternatives --install \
        /usr/bin/idlj idlj \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/idlj 1100

update-alternatives --install \
        /usr/bin/jar jar \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jar 1100

update-alternatives --install \
        /usr/bin/jarsigner jarsigner \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jarsigner 1100

update-alternatives --install \
        /usr/bin/javac javac \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/javac 1100

update-alternatives --install \
        /usr/bin/javadoc javadoc \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/javadoc 1100

update-alternatives --install \
        /usr/bin/javah javah \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/javah 1100

update-alternatives --install \
        /usr/bin/javap javap \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/javap 1100

update-alternatives --install \
        /usr/bin/jconsole jconsole \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jconsole 1100

update-alternatives --install \
        /usr/bin/jdb jdb \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jdb 1100

update-alternatives --install \
        /usr/bin/jhat jhat \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jhat 1100

update-alternatives --install \
        /usr/bin/jinfo jinfo \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jinfo 1100

update-alternatives --install \
        /usr/bin/jmap jmap \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jmap 1100

update-alternatives --install \
        /usr/bin/jps jps \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jps 1100

update-alternatives --install \
        /usr/bin/jrunscript jrunscript \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jrunscript 1100

update-alternatives --install \
        /usr/bin/jsadebugd jsadebugd \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jsadebugd 1100

update-alternatives --install \
        /usr/bin/jstack jstack \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jstack 1100

update-alternatives --install \
        /usr/bin/jstat jstat \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jstat 1100

update-alternatives --install \
        /usr/bin/jstatd jstatd \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/jstatd 1100

update-alternatives --install \
        /usr/bin/native2ascii native2ascii \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/native2ascii 1100

update-alternatives --install \
        /usr/bin/rmic rmic \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/rmic 1100

update-alternatives --install \
        /usr/bin/schemagen schemagen \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/schemagen 1100

update-alternatives --install \
        /usr/bin/serialver serialver \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/serialver 1100

update-alternatives --install \
        /usr/bin/wsgen wsgen \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/wsgen 1100

update-alternatives --install \
        /usr/bin/wsimport wsimport \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/wsimport 1100

update-alternatives --install \
        /usr/bin/xjc xjc \
    /usr/lib/jvm/java-7-openjdk-amd64/bin/xjc 1100

Please note that we used a priority value of 1100, so that we can assign Java 7 a higher priority than that of Java 6. Now, we run the above script, and check again the alternatives status, and where /etc/alternatives/javac points.

> update-alternatives --display javac


javac - auto mode
  link currently points to /usr/lib/jvm/java-7-openjdk-amd64/bin/javac
/usr/lib/jvm/java-6-openjdk-amd64/bin/javac - priority 1061
  slave javac.1.gz: /usr/lib/jvm/java-6-openjdk-amd64/man/man1/javac.1.gz
/usr/lib/jvm/java-7-openjdk-amd64/bin/javac - priority 1100
Current 'best' version is '/usr/lib/jvm/java-7-openjdk-amd64/bin/javac'.

Enjoy Java 7 again! Don't forget to change the default JVM path in Eclipse, though.

What about the man pages installed as slaves? That part is left as an exercise :-)

2012-02-27

Debian Wheezy : Removing unused locales and translations

Removing Locales

Debian includes several locales and translations in its default installation. Typically, we need very few of them, mostly just one! Here is how I removed unused locales and translations from my Debian Wheezy installation. This should apply to Sid too, but I have not verified it. The following steps should be executed as root.

  • Issue the command locale -a -v to see a full list of the locales currently installed. Should this list already match your requirement, you can skip the remainder of this section.
  • Edit (or create) the file /etc/default/locale. Include the entries for your desired locale. My file looks as follows.
  • #  File generated by update-locale
    LANG=en_IN
    LANGUAGE="en_IN:en"
    
  • Remove all the files in the directory /usr/lib/locale.
  • Now, regenerate the locales based on your default configuration.

Here is the sequence of steps.

> locale -a -v


> vi /etc/default/locale


> cd /usr/lib/locale
> rm -fr *

> locale-gen

Removing Translations

Unneeded translations consume disk space, network bandwidth (when updating or upgrading), and can potentially make glibc larger. To remove unused translations, execute the following steps as root.

> cd /etc/apt/apt.conf.d
> touch 99translations


> cat 99translations
Acquire::Languages "none";


> cd /var/lib/apt/lists
> rm -f *Translation*

If you want to be sure, you can reboot the system. Now, when you apt-get update or apt-get upgrade, you should no longer have unused translations checked for, updated or downloaded.

2012-01-09

Debian Wheezy : Running in VMware Fusion 4.1

Note: The following applies to Debian Sid as well.

Here is some information on how I could get Debian Wheezy to run successfully in VMware Fusion 4.1.

The installation itself was uneventful. Once Wheezy installed, I proceeded to unpack VMware Tools, and run the installation script. However, the version of VMware Tools that comes with VMware Fusion 4.1 does not work properly with kernel 3.2.x.

After a few failed attempts at patching the code and trying again, I uninstalled VMware Tools. I decided to try open-vm-tools instead.

Here is the sequence of steps that I executed (as root, of course).

  • apt-get update
  • apt-get install build-essential
  • apt-get install open-vm-tools

You will see some errors about modules not being available. It is normal. Please ignore them, and proceed.

  • apt-get install open-vm-dkms

The above should install dkms itself as a dependency. By the way, dkms is a system that can install dynamically loadable kernel modules. The above package contains the source code of the Open VM Tools kernel modules.

  • cd /usr/src
  • ls

You should see a directory for open-vm-tools. Please note the version number, which is the part after open-vm-tools-. Now, issue the command

  • dkms install open-vm-tools/<version>

where you should substitute the version number that you found out above. That installs the necessary kernel modules. It is necessary to create an appropriate entry in /etc/fstab for your host Mac's share. An example entry is shown here.

.host:/mac    /mnt/hgfs/mac    vmhgfs    defaults    0  1

For X automatic re-sizing and copy-and-paste between OS X and Wheezy, you have to install one last package.

  • apt-get install open-vm-toolbox

That is it. Now, reboot the virtual image, and enjoy your Debian Wheezy with better host integration!