Here's the output:
$  g++ -v -s -I/usr/include/boost -lboost_date_time -pthread ./timer.cpp -o ./timer
Using built-in specs.
Target: i486-pc-linux-gnu
Configured with: /var/tmp/portage/sys-devel/gcc-4.1.2/work/gcc- 4.1.2/configure --prefix=/usr --bindir=/usr/i486-pc-linux-gnu/gcc-bin/4.1.2 --includedir=/usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include --datadir=/usr/share/gcc-data/i486-pc-linux-gnu/4.1.2 --mandir=/usr/share/gcc-data/i486-pc-linux-gnu/4.1.2/man --infodir=/usr/share/gcc-data/i486-pc-linux-gnu/4.1.2/info --with-gxx-include-dir=/usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include/g++-v4 --host=i486-pc-linux-gnu --build=i486-pc-linux-gnu --disable-altivec --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --enable-secureplt --disable-libunwind-exceptions --disable-multilib --enable-libmudflap --disable-libssp --disable-libgcj --with-arch=i486 --enable-languages=c,c++,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
Thread model: posix
gcc version 4.1.2 (Gentoo 4.1.2 p1.0.2)
 /usr/libexec/gcc/i486-pc-linux-gnu/4.1.2/cc1plus -quiet -v -I/usr/include/boost -D_GNU_SOURCE -D_REENTRANT ./timer.cpp -quiet -dumpbase timer.cpp -march=i486 -auxbase timer -version -o /tmp/cc9RRPjp.s
ignoring nonexistent directory "/usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../../i486-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/boost
 /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include/g++-v4
 /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include/g++-v4/i486-pc-linux-gnu
 /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include/g++-v4/backward
 /usr/local/include
 /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/include
 /usr/include
End of search list.
GNU C++ version 4.1.2 (Gentoo 4.1.2 p1.0.2) (i486-pc-linux-gnu)
        compiled by GNU C version 4.1.2 (Gentoo 4.1.2 p1.0.2).
GGC heuristics: --param ggc-min-expand=46 --param ggc-min-heapsize=30755
Compiler executable checksum: 4ca4b00b3bea7fbbb8f68a78703ea1b5
 /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../../i486-pc-linux-gnu/bin/as -V -Qy -o /tmp/ccgiUm3Z.o /tmp/cc9RRPjp.s
GNU assembler version 2.16.1 (i486-pc-linux-gnu) using BFD version 2.16.1
 /usr/libexec/gcc/i486-pc-linux-gnu/4.1.2/collect2 --eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o ./timer -s /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../crt1.o /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../crti.o /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/crtbegin.o -L/usr/lib/gcc/i486-pc-linux-gnu/4.1.2 -L/usr/lib/gcc/i486-pc-linux-gnu/4.1.2 -L/usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../../i486-pc-linux-gnu/lib -L/usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../.. -lboost_date_time /tmp/ccgiUm3Z.o -lstdc++ -lm -lgcc_s -lgcc -lpthread -lc -lgcc_s -lgcc /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/crtend.o /usr/lib/gcc/i486-pc-linux-gnu/4.1.2/../../../crtn.o
/tmp/ccgiUm3Z.o: In function `__static_initialization_and_destruction_0(int, int)':
timer.cpp:(.text+0x13b): undefined reference to `boost::system::get_system_category()'
timer.cpp:(.text+0x145): undefined reference to `boost::system::get_posix_category()'
timer.cpp:(.text+0x14f): undefined reference to `boost::system::get_posix_category()'
timer.cpp:(.text+0x159): undefined reference to `boost::system::get_system_category()'
collect2: ld returned 1 exit status

On Nov 29, 2007 12:06 PM, <jayc.lawrence@gmail.com> wrote:
Hi Daniel,

I just did a little digging, regarding that particular error it has been
suggested previously to add -pthread to your compile string. Could you
give us more output like what other undefined references there are?

Jay

Daniel wrote:
> including the -I/path/to/boost seemed to do the trick, however, once I
> started utilizing it (asio/date_time) I started getting things such as
> undefined reference to `pthread_detach'
>
> Code directly taken from the tutorial here:
> http://asio.sourceforge.net/boost_asio_0_3_7/libs/asio/doc/tutorial/tuttimer1src.html
>
> Is there a list of the exact library names in boost/asio?
>
> On Nov 29, 2007 11:27 AM, <jayc.lawrence@gmail.com
> <mailto:jayc.lawrence@gmail.com>> wrote:
>
>     Hi Daniel,
>
>     Where were your boost header files and libraries compiled to? I had
>     similar issues and John Maddock helped me solve a path issue. Try adding
>
>     -I/path/to/boost
>
>     to your compile string e.g
>
>     g++ -v -s -I/path/to/boost myfile.cpp -o myfile.exe
>
>     you might need to add the relevant -lboost_library_name_goes_here to the
>     end of that compile string, where boost_library_name_goes_here is the
>     name of the library you are using.
>
>     I thought this would be easier on linux than windows to be honest and
>     here you are having some problems !
>
>     Hope this helps.
>
>     Jay
>
>     Daniel wrote:
>      > I wrote a simple "Hello, world!" program to test if boost/asio was
>      > working correctly:
>      >
>      > #include <iostream>
>      > #include <boost/date_time/posix_time/posix_time.hpp>
>      >
>      > int main()
>      > {
>      >   std::cout << "Hello, world!\n";
>      >   return 0;
>      > }
>      >
>      > But, I get this: (GCC C++ 4.1.2/Linux version 2.6.22-gentoo-r8)
>      > test.cpp:(.text+0x10b): undefined reference to
>      > `boost::system::get_system_category()'
>      > test.cpp:(.text+0x115): undefined reference to
>      > `boost::system::get_posix_category()'
>      > test.cpp:(.text+0x11f): undefined reference to
>      > `boost::system::get_posix_category()'
>      > test.cpp:(.text+0x129): undefined reference to
>      > `boost::system::get_system_category()'
>      >
>      >
>      > This happens when I used '#include
>      > <boost/date_time/posix_time/posix_time.hpp>'
>      > I can't figure out what I'm missing
>      >
>      >
>      >
>     ------------------------------------------------------------------------
>      >
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