I take this��opportunity��to also explain how to add 32 bit libraries for 64 bit ubuntu (in debian if I remember correctly should be the same) for future reference.
Open a console
Type the following:
sudo apt-get update && sudo apt-get install ia32-libs
You should be prompted to enter your password, type it and hit enter.
After the install finishes you should be able to run Pharo.
Maybe a note or warning should be put in the download section of the website to address this problem to newcomers.Something like "running linux on a amd64 architecture, read some_section_on_how_to_install_libraries"
Cheers
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Alan Rodas Bonjour