While executing proguard (via maven2) on MacOSX Snow Leopard, I’ve got the following error:

[proguard] Error: Can't read [/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/lib/rt.jar] (No such file or directory)

Similarly, you can also get the following error:

[proguard] Error: Can't read [/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/lib/jsse.jar] (No such file or directory)

That happens because the Java bundled with MacOSX doesn’t provide a standard library configuration, that is the rt.jar has been moved (as well as the jsse.jar library) and even renamed. To fix the issue simply symlink jsse.jar and symlink rt.jar to the corresponding classes.jar file:

localhost:~ root# cd /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/lib/  
localhost:lib root# ln -s ../../Classes/classes.jar rt.jar  
localhost:lib root# ln -s ../../Classes/jsse.jar .