Setting Rpath Order in Qmake

Qmake and passing $ORIGIN to linker option -rpath

If you want $ORIGIN to be (properly) evaluated while building you can simply add this to your .pro file:

QMAKE_RPATHDIR += $ORIGIN/../mylibs

RPATH in .pro-file not working

It is here "qmake and rpath":

You have to use the $ORIGIN feature of the runtime linker.
Unfortunately, due to some brilliant foresight of the loader devs,
they used '$' as prefix, which makes it a royal pain in the ass to
pass around. It's impossible to use it in QMAKE_RPATHDIR. You must
instead use:
QMAKE_LFLAGS += '-Wl,-rpath,\'\$$ORIGIN\''
so that it survives both the project file as well as the Makefile.

In your command line it goes to shell as -Wl,-rpath,$ORIGIN and $ORIGIN is expanded, since the $ dollar sign is interpreted by the shell. It should be quoted. Example of such quotation is also provided in LD.SO(8) man page: gcc -Wl,-rpath,'$ORIGIN/../lib'.

How do I enforce the order of qmake library dependencies?

The .pc file(s) for mylib1, mylib2 may be incomplete.

If those libraries depend on -lboost_date_time and -lboost_signals, then the .pc files should already pull in those dependencies by:

Libs: -lboost_date_time -lboost_signals

...and qmake will put them at the correct place in the link line. No need to explicitly put them in the .pro file :)

Setting rpath for dependencies of dependencies?

I ended up not doing anything at build time, and instead added a post-build step to my CMake where I run patchelf to change all the rpaths to $ORIGIN:

if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
    add_custom_command(
            TARGET Client POST_BUILD
                COMMAND find ${OUTPUT_DIR} -type f -maxdepth 1 -exec patchelf --set-rpath '\$\$ORIGIN' {} \\\;
    )
endif()

To be more complete for anyone reading around, the more-normal path is to have an install step where you put your files in the appropriate directories and make use of already-installed system shared libs. In my case an install step wouldn't be appropriate, so I'm adding custom commands after the build step to copy my dependencies into a directory with the executable and modify the rpath so they get loaded properly.

understanding external library path qmake

The statement -L"PATH" means add PATH the library search
directory list.
The statement -lOMD means load library OMD during linking.

It seems somehow your library is already in the library search path.
Which means LIBS += -lOMD will also work. Aside from some runtime libraries you have to specify the libraries to load.

edit:

/usr/lib is a default library search path. If you manually copy the library there, it will be found.

Change position of a variable in Makefile which is added to the Makefile via qmake

I found a way to handle the problem: If we use a global variable as the path to the library, it's not a good idea to set the rpath as follows:

QMAKE_LFLAGS += -Wl,--rpath=\\\$\CUSTOMPATH

Instead, we could use QMAKE_RPATHDIR:

QMAKE_RPATHDIR += $${CUSTOMPATH}