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Ruby Header Files OS-X Lion

If you try to install a ruby gem you are likely to receive the following error:

ERROR: Error installing caldecott:
ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
mkmf.rb can’t find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h

It clearly mocks about the missing ruby.h file. To overcome this issue you need to have XCode installed and there goto “Preferences/Downloads”

XCode Downloads

Download the “Command Line Tools”. Afterwards the gem installation should succeed with a breeze.

qemu-img error and version madness

The Ubuntu Precise 12.04 qemu version is fairly “outdated” stopping at around 1.0. The current qemu release candiate is 1.3.0.rc2 .

So if you are running into a

qemu-img: error while reading sector 131072: Invalid argument

error while converting images using qemu-img, just try to update your qemu binaries, by the provided source files of

apt-get install libglib2.0-dev dh-autoreconf

tar xvfj qemu-1.3.0-rc1.tar.bz2

cd qemu-1.3.0-rc1

./make install

The binaries will be under


So just for the sake of converting a full path to the qemu-img will do the trick:

/usr/local/bin/qemu-img convert disk1.vmdk -O qcow2 disk1.qcow2

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