RPATH equivalent for executables

I have a c++ shared library which as part of its normal behaviour fork()/execs() another executable containing some unstable legacy code. This executable is not useful other than with this library, so I'd like to avoid placing it in a PATH directory. I'd also like to be able to install multiple copies in various locations, so hard coded paths are not desirable. Is there anything equivalent to a RPATH that will allow exec() to find this executable? Alternatively, is it possible to query the rpath of a shared library from the library itself?

Edit: This p开发者_开发知识库ost suggests the latter is possible. I'll leave this open in case anybody knows the answer to the asked question. Is there a way to inspect the current rpath on Linux?

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You can always use getenv to get the environment within the shared object, but is RPATH really what you want to use for that? Wouldn't it be better to have the shared object have some sort of configuration file in the user's home directory (or custom environment variable) that tells it which location to use run the external binary?

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I think the best way to do this is to set an environment variable and use execve() to run the binary. Presumably you could just set PATH and then execve() a shell that would use PATH to find a copy of the executable. The library equivalent would be to set LD_LIBRARY_PATH and execve() a binary that has this library as a dependency.

In either case, you are not changing the external environment, only manufacturing a modified copy that is used with execve().