LIBRARY_PATH not used before /usr/lib anymore in gcc 4.2 and later?

[Andrew Haley]

Frederik wrote:
> On Wed, 11 Jun 2008 13:46:45 +0100, Andrew Haley wrote:
> 
>> What does readelf -d test say?
> 
> $ echo $LIBRARY_PATH
> /cvos/shared/apps/gcc/gcc-4.2.4//lib:/cvos/shared/apps/boost/gcc-4.2/1.35.0/lib

I'm not sure this will have any effect.

> $ echo $LD_LIBRARY_PATH
> /cvos/shared/apps/gcc/gcc-4.2.4//lib:/cvos/shared/apps/boost/gcc-4.2/1.35.0/lib:/cvos/shared/apps/sge/6.1/lib/lx26-amd64

This should work, though.

> $ g++ -o test test.cpp -lboost_regex

Use `gcc -v' here.  Let's see what that says.

> $ readelf -d test
> 
> Dynamic section at offset 0xf778 contains 24 entries:
>   Tag        Type                         Name/Value
>  0x0000000000000001 (NEEDED)             Shared library: [libboost_regex.so.2]

Right, so it's liked against libboost_regex.so.2.  The first instance of
libboost_regex.so.2 that is found in LD_LIBRARY_PATH will be used.

> $ ls -l /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/*regex*
> lrwxrwxrwx 1 root root      27 Jun 11 12:22 /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/libboost_regex-mt.so -> libboost_regex-mt.so.1.35.0
> -rwxr-xr-x 1 root root 5881209 Jun 11 12:22 /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/libboost_regex-mt.so.1.35.0
> lrwxrwxrwx 1 root root      24 Jun 11 12:21 /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/libboost_regex.so -> libboost_regex.so.1.35.0
> -rwxr-xr-x 1 root root 5881164 Jun 11 12:21 /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/libboost_regex.so.1.35.0
> 
> So here I would have expected it to link against libboost_regex.so.1.35.0 
> instead of libboost_regex_so.2. What am I doing wrong here?

I'm not sure yet.

Andrew.



     The linker uses the following search paths to locate required
     shared libraries:
       1. Any directories specified by `-rpath-link' options.

       2. Any directories specified by `-rpath' options.  The difference
          between `-rpath' and `-rpath-link' is that directories
          specified by `-rpath' options are included in the executable
          and used at runtime, whereas the `-rpath-link' option is only
          effective at link time. Searching `-rpath' in this way is
          only supported by native linkers and cross linkers which have
          been configured with the `--with-sysroot' option.

       3. On an ELF system, if the `-rpath' and `rpath-link' options
          were not used, search the contents of the environment variable
          `LD_RUN_PATH'. It is for the native linker only.

       4. On SunOS, if the `-rpath' option was not used, search any
          directories specified using `-L' options.

       5. For a native linker, the contents of the environment variable
          `LD_LIBRARY_PATH'.

       6. For a native ELF linker, the directories in `DT_RUNPATH' or
          `DT_RPATH' of a shared library are searched for shared
          libraries needed by it. The `DT_RPATH' entries are ignored if
          `DT_RUNPATH' entries exist.

       7. The default directories, normally `/lib' and `/usr/lib'.

       8. For a native linker on an ELF system, if the file
          `/etc/ld.so.conf' exists, the list of directories found in
          that file.