print `LD_LIBRARY_PATH="/local/gnu/lib/:/local/lib/:\$LD_LIBRARY_PATH"
+`;
print `EXPORT LD_LIBRARY_PATH`;
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That's not going to work. That will set the environment var in your subshell but when you return from the backtick call the variable will be gone. See programatically setting the LD_LIBRARY_PATH (especially the comment from tye)