Error: Unable to access jarfile /lib/mxmlc.jar
I found that this happens when *duh* the mxmlc.jar file cannot be found. Now if we do a vim on the mxmlc file we can see that if we do NOT set the path of the "$FLEX_HOME" var that it will default to wherever mxmlc is located. This should be fine but in some cases wont work if you are calling mxmlc in a odd or different way (i.e. using symlinks or something like that).
To solve this you can add this into your "mxmlc" file.
This should fix any build errors you have when running a flex build via script or using odd/different methods....