Changing linked library for a given executable (CentOs 6)

librarieslinker

I have an executable linked like this:

  $ ldd a.out
        libboost_system-mt.so.1.47.0 => /usr/lib64/libboost_system-mt.so.1.47.0 (0x00007f4881f56000)
        libssl.so.10 => /usr/lib64/libssl.so.10 (0x00007f4881cfb000)
        libcrypto.so.10 => /usr/lib64/libcrypto.so.10 (0x00007f4881965000)
        librt.so.1 => /lib64/librt.so.1 (0x00007f488175d000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f4881540000)
        libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00007f4881239000)
.
.

Where the libcrypto and libssl libraries are openssl 1.0.0-fips libs. I want to experiment with the 1.0.1 libraries instead, and so I've built them in my home directory. Is there a way to get a.out to relink against my new openssl libraries without a lot of pain? I would like to avoid

  • Having to relink a.out (because the build tools are massively complicated)
  • Altering any global settings (because other devs work on this machine)

Is it possible to do what I'm hoping here?

Best Answer

You can temporarily substitute a different library for this particular execution. In Linux, the environment variable LD_LIBRARY_PATH is a colon-separated set of directories where libraries should be searched for first, before the standard set of directories; this is useful when debugging a new library or using a nonstandard library for special purposes. The environment variable LD_PRELOAD lists shared libraries with functions that override the standard set, just as /etc/ld.so.preload does. - Shared Libraries

You can also invoke the loader directly:

/lib/ld-linux.so.2 --library-path path executable

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