Is it possible to detect 32 bit vs 64 bit in a bash script? [duplicate]

I am writing a bash script to deal with some installations in an automated way... I have the possibility of getting one such program in 32 or 64 bit binary... is it possible to detect the machine architecture from bash so I can select the correct binary?

This will be for Ubuntu machines.

MACHINE_TYPE=`uname -m`
if [ ${MACHINE_TYPE} == 'x86_64' ]; then
  # 64-bit stuff here
else
  # 32-bit stuff here
fi

getconf LONG_BIT seems to do the trick as well, which makes it even easier to check this since this returns simply the integer instead of some complicated expression.

if [ `getconf LONG_BIT` = "64" ]
then
    echo "I'm 64-bit"
else
    echo "I'm 32-bit"
fi

Does

uname -a

give you anything you can use? I don't have a 64-bit machine to test on.

Note from Mike Stone: This works, though specifically

uname -m

Will give "x86_64" for 64 bit, and something else for other 32 bit types (in my 32 bit VM, it's "i686").