The mimetypes module can be used to determine a files MIME type.

#!/usr/bin/python3
import mimetypes
filetype = mimetypes.MimeTypes().guess_type('/path/to/example.png')
print(f"example.pdf MIME type = {filetype}")

filetype = mimetypes.MimeTypes().guess_type('/path/to/example.pdf')
print(f"example.pdf MIME type = {filetype}")

In this example, the following should be returned.

example.png MIME type = ('image/png', None)
example.pdf MIME type = ('application/pdf', None)

Or better yet, return index 0 to just get the MIME type.

#!/usr/bin/python3
import mimetypes
filetype = mimetypes.MimeTypes().guess_type('/path/to/example.png')
print(f"example.png MIME type = {filetype[0]}")

filetype = mimetypes.MimeTypes().guess_type('/path/to/example.pdf')
print(f"example.pdf MIME type = {filetype[0]}")

Which should now return the following.

example.png MIME type = 'image/png'
example.pdf MIME type = 'application/pdf'

Or, using the magic module. To use the magic module, you will need to install the python-magic packages.

pip install python-magic

Then do something like this to return the MIME type.

#!/usr/bin/python3
import magic
mime = magic.Magic(mime=True)

mimetype = mime.from_file('/path/to/example.png')
print(f"example.png MIME type = {mimetype}")

mimetype = mime.from_file('/path/to/example.pdf')
print(f"example.pdf MIME type = {mimetype}")

Which should now return the following.

example.png MIME type = image/png
example.pdf MIME type = application/pdf