gcc - correct usage of rpath (relative vs absolute)

Question

When building a binary or library, specifying the rpath, i.e.

-Wl,rpath,<path/to/lib>

tells the linker where to find the required library at runtime of the binary.

What is the UNIX philosphy regarding absolute and relative paths here? Is it better to use an absolute path so the lib can be found from everywhere? Or is it better to make it relative so copying an entire directory or renaming a higher level path won't render the binary unusable?

Update

Using $ORIGIN is usually the preferred way of building binaries. For libraries I like to put in the absolute path, because otherwise you won't be able to link to the library. A symbolic link will change the $ORIGIN to point to the path of the link and not of the link target.

Answer 1

In the case of rpath, it makes no sense to use a relative path, since a relative path will be relative to the current working directory, NOT relative to the directory where the binary/library was found. So it simply won't work for executables found in $PATH or libraries in pretty much any case.

Instead, you can use the $ORIGIN "special" path to have a path relative to the executable with
-Wl,-rpath,'$ORIGIN' -- note that you need quotes around it to avoid having the shell interpret it as a variable, and if you try to do this in a Makefile, you need $$ to avoid having make interpret the $ as well.