text/html; firefox '%s' &; test=test -n "$DISPLAY"; needsterminal;
text/html; w3m -I %{charset} -T text/html; copiousoutput;
text/plain; less -N %s; copiousoutput;
application/pdf; firefox '%s'
application/zip; unzip -p '%s' | less -N
image/png; feh '%s'
image/jpg; feh '%s'
image/jpeg; feh '%s'
image/gif; feh '%s'