I'm using Ubuntu 12.04 LTS version. I've tried the steps suggested by 'amo-ej1', but my 'dpkg' didn't have 'add' or 'architecture' options.
However, the following worked for me:
1) Install 'adb' and 'fastboot' provided by the following third-party PPA.
sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install android-tools-adb android-tools-fastboot
2) Replace the copy of 'adb' and 'fastboot' provided by the official Android SDK with those installed from the above step:
cp /usr/bin/adb <path-to-your-adt-sdk-package>/sdk/platform-tools/adb
cp /usr/bin/fastboot <path-to-your-adt-sdk-package>/sdk/platform-tools/fastboot
3) Restart(re-execute) your eclipse binary.
Full credits:
http://www.webupd8.org/2012/08/install-adb-and-fastboot-android-tools.html
IMPORTANT EDIT (ALTERNATE SOLUTION):
Although the above would resolve your error (and you can proceed with the Android App tutorial), as I found, ADT will also need 'aapt' (another 32-bit binary) located in:
<path-to-your-adt-sdk-package>/sdk/build-tools/android-x.x/
And unfortunately, the link that I provided above doesn't provide this binary.
So, here's my other solution:
1) Update your system
Open 'Update Manager' => 'Settings' => 'Updates
Check "Recommended Updates (precise updates)"
Update the updates that are being shown
2) Install ia32-libs
sudo apt-get install ia32-libs
And I finally was able to install 'ia32-libs'. To know why 'ia32-libs' wouldn't install in the first place, please read the answer posted by 'slangasek' here:
https://askubuntu.com/questions/136394/cannot-install-ia32-libs
ia32-libs-multiarch
and its 700 MB of dependencies. – Mariande