I got this error when trying to export a signed apk in Eclipse
Error while running zipalign: Unable to open as zip archive
I have run the Help->Check for Updat
In my case, I ran the command from the directory where the unsigned apk was and it ran perfectly.
cd /platforms/android/build/outputs/apk zipalign -v 4 android-release-unsigned.apk signed.apk
This way, I didn't need to worry about specifying the directory.
ps: I did this on ubuntu.