mod rewrite - fallback aliased directory for static files that don't exist -

current configuration:

alias   /wcsstore       "/opt/ibm/websphere/appserver/profiles/demo/installedapps/wc_demo_cell/wc_demo.ear/stores.war" 

example url:

http://okdemo/wcsstore/test.txt 

how make first existing file /opt/ibm/test/test.txt , use original directory fallback?

tried:

rewritecond %{request_filename} !-f rewriterule ^/wcsstore/(.*) /wcsstore-old/$1 [pt,l]  alias   /wcsstore       "/opt/ibm/test" alias   /wcsstore-old       "/opt/ibm/websphere/appserver/profiles/demo/installedapps/wc_demo_cell/wc_demo.ear/stores.war" 

but seems request_filename not resolve /opt/ibm/test/test.txt. served fallback dir:

rewritecond: input='/wcsstore/test.txt' pattern='!-f' => matched 

maybe should concatenate: /opt/ibm/test%{request_uri} , how remove /wcsstore word before concatenation?

in virtualhost context request_filename same request url, since nothing has been mapped yet. prefix %{document_root}/ poke around, or other explicit path.

to remove "wcstore", use rewritecond split string , use %1 instead of original variable

rewritecond %{request_uri} ^/wcsstore/(.*) rewriterule /var/www/.../%1 ! -f