linking error in boost asio - c++

Question

I am getting below linking error while compiling a simple piece of code using pthread.
The system i am working on is x86_64 (gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-11) and am compiling as -
gcc -lpthread ~/temp/temp.cpp -lrt -L"/usr/lib/x86_64-redhat-linux5E/lib64/".
Its evident that the problem is with pthread library. So i have two questions.
Q1. is it fine to use x64 pthread libs with x86 code. (In this piece of code it doesnt matter but it does in my usage) (I guess its not but how might i differentiate between x64 and x86 libs?)
Q2. i see pthread and lrt both are present at /usr/lib but even if i give that path it says -lpthread not found.
What am i missing here? Thanks for your help.
Error :
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x12): undefined reference to `__libc_csu_fini'
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x19): undefined reference to `__libc_csu_init'
/tmp/cc2GQOUf.o:(.eh_frame+0x12): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status
Code :
#include <stdio.h>
#include <pthread.h>
int main()
{
pthread_t f1_thread;
return 0;
}

Answer 1

In compilation phase,compiler can use gcc or g++,but g++ will call gcc command automatically.But in link phase,linker can use g++ or gcc -lstdc++.Because the gcc command cannot link with the libraries that be used by c++ program automatically, so usually use g++to complete the link.
So the command g++ -g -lpthread ~/temp/temp.cpp -o temp should be ok.