Re: Linking against shared objects that reside at different paths on link-time versus runtime?

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 27 June 2011 19:24, Jonathan Wakely wrote:
>
> To ensure the library can be found at runtime, use LD_LIBRARY_PATH, or
> better use RPATH:

I forgot to add, you can investigate how the runtime linker finds the
dependencies using LD_DEBUG

$ LD_DEBUG=libs ldd ./a.out
      ...
      7061:     find library=libyyy.so [0]; searching
      7061:      search path=/tmp/tls/x86_64:/tmp/tls:/tmp/x86_64:/tmp
         (RPATH from file ./a.out)
      7061:       trying file=/tmp/tls/x86_64/libyyy.so
      7061:       trying file=/tmp/tls/libyyy.so
      7061:       trying file=/tmp/x86_64/libyyy.so
      7061:       trying file=/tmp/libyyy.so
      7061:
      ...
        libyyy.so => /tmp/libyyy.so (0x00002b87148fd000)


$ rm libyyy.so
$ LD_DEBUG=libs LD_LIBRARY_PATH=/tmp/lib ldd ./a.out
      ...
      7097:     find library=libyyy.so [0]; searching
      7097:      search path=/tmp/tls/x86_64:/tmp/tls:/tmp/x86_64:/tmp
         (RPATH from file ./a.out)
      7097:       trying file=/tmp/tls/x86_64/libyyy.so
      7097:       trying file=/tmp/tls/libyyy.so
      7097:       trying file=/tmp/x86_64/libyyy.so
      7097:       trying file=/tmp/libyyy.so
      7097:      search
path=/tmp/lib/tls/x86_64:/tmp/lib/tls:/tmp/lib/x86_64:/tmp/lib
 (LD_LIBRARY_PATH)
      7097:       trying file=/tmp/lib/tls/x86_64/libyyy.so
      7097:       trying file=/tmp/lib/tls/libyyy.so
      7097:       trying file=/tmp/lib/x86_64/libyyy.so
      7097:       trying file=/tmp/lib/libyyy.so
      7097:      search cache=/etc/ld.so.cache
      7097:      search
path=/lib64/tls/x86_64:/lib64/tls:/lib64/x86_64:/lib64:/usr/lib64/tls/x86_64:/usr/lib64/tls:/usr/lib64/x86_64:/usr/lib64
               (system search path)
      7097:       trying file=/lib64/tls/x86_64/libyyy.so
      7097:       trying file=/lib64/tls/libyyy.so
      7097:       trying file=/lib64/x86_64/libyyy.so
      7097:       trying file=/lib64/libyyy.so
      7097:       trying file=/usr/lib64/tls/x86_64/libyyy.so
      7097:       trying file=/usr/lib64/tls/libyyy.so
      7097:       trying file=/usr/lib64/x86_64/libyyy.so
      7097:       trying file=/usr/lib64/libyyy.so
      ...
        libyyy.so => not found