What path does @loader_path resolve to?

Question

I'm having a hard time understanding the absolute path that a @loader_path within a file refers to.

user@local:~$ otool -L zlib.so 
zlib.so:
    @loader_path/../../libz.1.dylib (compatibility version 1.0.0, current version 1.2.7)
    /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 111.0.0)

I want to know where the system looks to find libz.1.dylib.

From some Mac documentation:

@loader_path/ This variable is replaced with the path to the directory containing the mach-o binary which contains the load command using @loader_path. Thus, in every binary, @loader_path resolves to a different path

I would have guessed this means that @loader_path is just the path to the object file (zlib.so), but that doesn't seem to be true.

Is there any command line utility that will resolve @loader_path to the actual path that is used when attempting to open a library?

Answer 1

Your guess is right: in this case @loader_path is the path to the directory, containing zlib.so. But there probably will be problems with using this lib. Where did you get that lib? If you are building it by yourself, see this question for some info.
The @loader_path is useful for the frameworks and plugins, but not for the standalone libraries.