Maybe it would be a good idea to do so as run-mailcap does :

theregrunner@mint17 : ~ € run-mailcap --debug "';xterm;#'.txt"
 - parsing parameter "';xterm;#'.txt"
 - Reading mime.types file "/etc/mime.types"...
 - extension "txt" maps to mime-type "text/plain"
 - Reading mailcap file "/etc/mailcap"...
Processing file "';xterm;#'.txt" of type "text/plain" (encoding=none)...
 - checking mailcap entry "text/plain; less '%s'; needsterminal"
 - program to execute: less '%s'
 - filename contains shell meta-characters; aliased to '/tmp/fileV7f2MZ'
 - executing: less '/tmp/fileV7f2MZ'
theregrunner@mint17 : ~ €