When compile HTK on 64bit machines, by default it will still try to compile the tools to 32bit. Then there will be an error after issue the command "make all":
/usr/include/gnu/stubs.h:7:27: fatal error: gnu/stubs-32.h: No such file or directory
To solve this problem, what we need is to install the multilib package for the gcc and g++. On Ubuntu, install following packages:
and redo "make all".