I have built HEADAS 6.3 from source code and I am initializing it before SAS. Now when I run any HEADAS command, it fails with the error ...xmmsas_20070708_1801/libextra/libgcc_s.so.1: version `GCC_4.2.0' not found (required by /usr/lib/libstdc++.so.6) . What is the problem and what can I do?

Most users of HEADAS Xspec need to build the whole HEADAS software from source code in order to be able to develop their own spectral models. When they do this on the latest distributions of Linux (Fedora Core 5 and 6, Ubuntu, etc), they will use in most of the cases a version of the GNU C/C++ compiler (gcc), which is incompatible with the version of gcc used to build SAS 7.1.0 (gcc 3.3.6).

Starting with gcc 3.4.X and continuing with gcc 4.X, any binary built with these versions of gcc requires a libgcc_s.so.1 library which is incompatible with the same library for gcc 3.3.X, despite of having the same name.

The reason of the error when running any HEADAS binaries after SAS is initialized last is that due to the order set by the SAS initialization to the LD_LIBRARY_PATH variable (DLYD_LIBRARY_PATH on Mac OS X), the libgcc_s.so.1 found does not contain the required elements for such binaries to be able to run properly.

The only final solution to avoid definitely such a problem is to build SAS with an updated gcc version like 4.X. But unfortunately such a simple solution has a substantial cost in terms of source code update, in order to adapt it to the new requirements of the updated gcc.

The only temporary workaround for this situation is to open a new terminal window, where SAS is not initiallized, and work there only with HEADAS.