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How to use dylib in Mac OS X (C++)

Asked 2011-01-13T05:21:32.973
37

I made an application (an executable) calling some dylib successfully. However, the dylib files and the executable are in different directory. I added the directory contains dylib files to the $PATH environment variable. However, it still doesn't load. I copy all the dylib files to the executable, the program finally runs. This confirms the dylib files have no problem. However, how can I tell the OS to find it?
In windows, I just need to add the directory path contains dll files to $PATH. What do I need to do for Mac OS X?

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2 Answers

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After reading the link that Justin provided, I was successfully able to use the @executable_path token to change my dylib install_name to point to the same dir where my executable is located.

@executable_path Absolute paths are annoying. Sometimes you want to embed a framework into an application instead of having to install the framework into /Library or a similar location.

The Mac's solution to this is @executable_path. This is a magic token that, when placed at the beginning of a library's install name, gets expanded to the path of the executable that's loading it, minus the last component. For example, let's say that Bar.app links against Foo.framework. If Bar.app is installed in /Applications, @executable_path will expand to /Applications/Bar.app/Contents/MacOS. If you intend to embed the framework in Contents/Frameworks, then you can just set Foo.framework's install name to @executable_path/../Frameworks/Foo.framework/Versions/A/Foo. The dynamic linker will expand that to /Applications/Bar.app/Contents/MacOS/../Frameworks/Foo.framework/Versions/A/Foo and will find the framework there.

http://www.mikeash.com/pyblog/friday-qa-2009-11-06-linking-and-install-names.html

I will demonstrate with an example.

Let's say I have the following executable /opt/local/bin/convert and its dylibs are in /opt/local/lib. I want to copy it to another dir and have it load its dylibs from the same directory as where I copied the executable.

> mkdir ~/tmp/bin
> cp /opt/local/bin/convert ~/tmp/bin

Get a list of the executables dylibs

> otool -L ~/tmp/bin/convert
~/tmp/bin/convert:
    /opt/local/lib/libtiff.3.dylib (compatibility ver
answered 2012-07-20T18:46:06.910
6
answered 2011-01-13T05:30:30.247

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