Dear everybody, we need to backport boost 1.49.0 to Redhat 5.2. b2 ; b2 install --prefix=/usr/local succeeds and installs libraries and headers in /usr/local as requested (g++ 4.1.2-42, 32 bit PAE kernel). However, we have a problem even linking a mostly trivial example: #include <boost/filesystem.hpp> int main () { copy_file(boost::filesystem::path("atest"), boost::filesystem::path("btest")); } $ g++ testBoost.cpp -lboost_filesystem -lboost_system /tmp/cc10doAS.o: In function `boost::filesystem3::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&)': testBoost.cpp: (.text._ZN5boost11filesystem39copy_fileERKNS0_4pathES3_[boost::filesystem3::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&)]+0x24): undefined reference to `boost::filesystem3::detail::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&, boost::filesystem3::copy_option::enum_type, boost::system::error_code*)' collect2: ld returned 1 exit status The symbol is present in /usr/local/lib/libboost_filesystem and ldconfig does know about its location (see below). Also, trying to link statically or adding -pthread does not change the situation. We are desperate for advice... Roald and Stefan. $ nm -C /usr/local/lib/libboost_filesystem.so | grep 'boost::filesystem3::detail::copy_file' 00010ae0 T boost::filesystem3::detail::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&, boost::filesystem3::copy_option::enum_type, boost::system::error_code*) $ cat /etc/ld.so.conf include ld.so.conf.d/*.conf /usr/local/lib