To make this webapp redirect to i.e. alfresco share, when you type <server name>:<tomcat port> in your browser, but this in your tomcat/webapps/index.jsp file:
<% response.sendRedirect("/share"); %>
If there is an index.html og index.htm file remove it.
Now index.jsp will redirect and you do not need to change the share-webapp
Note: there is other ways using Tomcat context and stuff