...
| Code Block |
|---|
swimas
|-- etc
| `-- modulefiles
| `-- xmllib
| |-- 4.0-GCC-6.1.0
| `-- 4.0-intel-17.0.4
`-- extra
`-- xmllib
|-- 4.0-GCC-4.8.5
| |-- include
| | |-- f90_file_reader.mod
| | |-- mod_f90_kind.mod
| | |-- string_manipulation_tools.mod
| | |-- xml2eg_mdl.mod
| | |-- xml_file_reader.mod
| | |-- xmllib_parser.mod
| | |-- xmllib_pathquery.mod
| | `-- xmllib_types.mod
| `-- lib
| |-- libxmllib.a
| `-- pkgconfig
| `-- xmllib.pc
|-- 4.0-intel-17.0.4
| |-- include
| | |-- f90_file_reader.mod
| | |-- mod_f90_kind.mod
| | |-- string_manipulation_tools.mod
| | |-- xml2eg_mdl.mod
| | |-- xml_file_reader.mod
| | |-- xmllib_parser.mod
| | |-- xmllib_pathquery.mod
| | `-- xmllib_types.mod
| `-- lib
| |-- libxmllib.a
| `-- pkgconfig
| `-- xmllib.pc
`-- lib
|-- libxmllib-4.0-GCC-4.8.5.a -> ../4.0-GCC-4.8.5/lib/libxmllib.a
`-- libxmllib-4.0-intel-17.0.4.a -> ../4.0-intel-17.0.4/lib/libxmllib.a |
RPATH - compiling codes with fixed location of libraries
One of the drawbacks of the module based layout is the problem of pointing to proper library (if we don't have symbolic links with fully qualified names).
This issue can be solved with rpath while compiling the code. Instead of having number of libraries, each with slightly different name, we can use rpath instead.
| Code Block | ||
|---|---|---|
| ||
gcc -o $@ $< -Iinclude -Llib -lshared -Wl,-rpath,$(CURDIR)/lib |
This way, each code will refer to version of library used for linking.
| Pros | Cons |
|---|---|
| different codes can use different versions of libraries | with each release of new version of the library user's code must be recompiled |
| each library is released as a separate installation (it's easy to maintain each version separately) | it's not possible to move libraries from their original location |
| we are not forced to build log LD_LIBRARY_PATH variables | |
| LD_LIBRARY_PATH has lower precedence than rpath | |
| It is still possible to use LD_PRELOAD to enforce given library to be used (e.g. debugging purposes) |