64-bit? 32-bit? How does a 32-bit program run in 64-bit Linux?

Installed is 64-bit ubuntu12.04, and just upgrade the kernel to 3.2.4, download the arm-eabi-4.4.3 from the Internet after decompression, but found that unable to run, run the prompt: no such file or directory

This is strange. It is clear that the problem does not exist? If you think about it, it may be related to my 64-bit system. view the arm-Linux-GCC information:

Rebi @ freedom :~ /Downloads/arm-eabi-4.4.3/bin $ file arm-Eabi-gcc
Arm-Eabi-GCC: Elf 32-bit LSB executable, Intel 80386, Version 1 (sysv), dynamically linked (uses SHARED libs), for GNU/Linux 2.6.8, not stripped

Check that the information of other executable programs on the system is indeed different from this:

Rebi @ freedom :~ /Downloads/arm-eabi-4.4.3/bin $ File/bin/mv
/Bin/MV: Elf 64-bit LSB executable, x86-64, Version 1 (sysv), dynamically linked (uses SHARED libs), for GNU/Linux 2.6.24, buildid [sha1] = 0x0d421df1996b245ce8fd3ff099ec88c8f6c50fec, stripped

It is suspected that it is a 32-bit 64-bit problem.

I found it on the internet is indeed this reason, of course, in Ubuntu to solve this problem is also very simple, as long as the installation of ia32-libs on the line:

Sudo apt-Get install ia32-libs

It seems that Linux is not as convenient as windows, and the 64-bit Windows 7 has never encountered such a problem.