This is an R package for mapping filename extensions to MIME types, based on the data derived from /etc/mime.types.
# installation
install.packages('mime')
library(mime)
guess_type(c('a/b/c.html', 'd.pdf', 'e.odt', 'foo.docx', 'tex'))
# [1] "text/html"
# [2] "application/pdf"
# [3] "application/vnd.oasis.opendocument.text"
# [4] "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
# [5] "text/x-tex"