Ya I tried using permissionDefinitions.xml file with this I can only apply permissions to content(i.e.,folder or a document). But My requirement is I need to display link in Alfresco header bar based on Roles.
For example : I need to display some options to Project Manager based on Role.
for that you need to do the customization in the script related to header bar. did in to the code and find out which webscript is responsible for rendering the header bar and then make changes in the ftl or js of that script to achieve what you are looking for.