Setting a System Wide path in Mac Yosemite

Question

I have installed boost libraries. I am using Eclipse to make a simple boost project.

#include <stdio.h>
#include <boost/filesystem.hpp>

int main() {
    boost::filesystem::path path("/Users/schoen"); // random pathname
   bool result = boost::filesystem::is_directory(path);
    printf("Path is a directory : %d\n", result);
    return 0;
}

I have already set the path of include folder and library folder in the properties of this project. But I was getting a runtime error: dyld: Library not loaded: libboost_system.dylib . To solve this problem, I went to run configuration and set the environment variable DYLD_LIBRARY_PATH to /Users/myName/Documents/Softwares/boost_1_59_0/stage/lib . This has solved my problem.

What I need: I don't want to set the environment variable for each Boost-based project. Therefore, I tried to set my .bash_profile . I wrote the following lines in .bash_profile .

# Following lines are for Boost Library
DYLD_LIBRARY_PATH=/Users/myName/Documents/Softwares/boost_1_59_0/stage/lib
export DYLD_LIBRARY_PATH

PROBLEM: By setting the variable in .bash_profile , I am able to run my program through the terminal. The program also runs if I open the IDE (eg Eclipse) via terminal and then run the application. Apparently, .bash_profile can set the variable for terminal applications. How can I set the path for windowed applications too?

PS: This path setting problem is not just for Boost only, but I have to do similar things for other libraries too (such as OpenCV which is build/installed in a local directory).

Answer 1

Rather than adding a system wide path like this, you should add the rpath to the libraries to applications that depend on boost. To add the rpath option, you do Project Properties -> C/C++ Build -> Settings -> Miscellaneous and in the linker flags add:

-Wl,-rpath,/Users/myName/Documents/Softwares/boost_1_59_0/stage/lib

(this is if your linker is g++ or clang++ , for example)

If your linker is ld explicitly, then the option is

-rpath /Users/myName/Documents/Softwares/boost_1_59_0/stage/lib

although you may need to add -macos_version_min 10.5 (or newer - probably 10.8 - this depends on the OS you're building on).

This will cause any applications built to search there for libraries as well as the default locations.

Although a location like that to me looks a bit volatile

Turns out that boost builds without setting the library name to include @rpath in the install name, which means that even when you set the -rpath in the build, because the libraries aren't mentioned to be in the @rpath , it won't find them at run time. A workaround to this is to explicitly set the install name for the boost libraries, and their internal references to their own libraries:

#!/bin/bash -p 

for i in *.dylib; do 
    # set the rpath 
    install_name_tool -id @rpath/$i $i 
    for lib in $(otool -L $i | grep libboost | awk '{print $1}'); do 
        if [[ -f $lib ]]; then 
            install_name_tool -change $lib @rpath/$lib $i 
        fi 
    done 
done 

This means the binaries that are linked to these boost libraries will respect the rpath setting.

You can repeat a similar process for other libraries to ensure that they respect rpath. The key element is the install_name_tool -id "@rpath/libstuff.dylib" libstuff.dylib , which says that when you link to the library record a reference to @rpath/libstuff.dylib . If libraries don't already have this set.

Secondly, for internal references to dependent libraries, the -change option alters references to the absolute name to an rpath relative name eg install_name_tool -change "libstuff.dylib" "@rpath/libstuff.dylib" libdependsonlibstuff.dylib . This can even be performed on a linked binary.

If you still want to set an environment variable, there are some options available which should help you getting a solution which works in that case.