diff --git a/ui/fixtures/cmd.auto.json b/ui/fixtures/cmd.auto.json
new file mode 100644
index 0000000..b34a966
--- /dev/null
+++ b/ui/fixtures/cmd.auto.json
@@ -0,0 +1,31 @@
+[
+{
+	"title": "gen ident",
+	"cmd": [ "genident", "name=A Test User" ],
+	"exit": 0
+},
+{
+	"title": "Test auto detection of file",
+	"cmd": [ "auto", "test.txt" ],
+	"stdin": "y\n",
+	"stdout": "Set:\n\tmimetype:\ttext/plain; charset=us-ascii\n\nApply (y/N)?\n"
+},
+{
+	"title": "Verify modification",
+	"cmd": [ "list", "test.txt" ],
+	"stdin": "y\n",
+	"stdout_re": ".*mimetype:\ttext/plain; charset=us-ascii.*"
+},
+{
+	"title": "Test auto detection of jpeg file",
+	"cmd": [ "auto", "z.jpg" ],
+	"stdin": "y\n",
+	"stdout": "Set:\n\tmimetype:\timage/jpeg\n\nApply (y/N)?\n"
+},
+{
+	"title": "Verify modification",
+	"cmd": [ "list", "z.jpg" ],
+	"stdin": "y\n",
+	"stdout_re": ".*mimetype:\timage/jpeg"
+}
+]
diff --git a/ui/fixtures/testfiles/z.jpg b/ui/fixtures/testfiles/z.jpg
new file mode 100644
index 0000000..0a64329
Binary files /dev/null and b/ui/fixtures/testfiles/z.jpg differ
diff --git a/ui/medashare/cli.py b/ui/medashare/cli.py
index 0210b7b..0abe77d 100644
--- a/ui/medashare/cli.py
+++ b/ui/medashare/cli.py
@@ -20,6 +20,7 @@ import hashlib
 import io
 import itertools
 import json
+import magic
 import os.path
 import pathlib
 import pasn1
@@ -670,7 +671,7 @@ def enumeratedir(_dir, created_by_ref):
 	Returned is a list of FileObjects.'''
 
 	return [FileObject.from_file(os.path.join(_dir, x),
-	    created_by_ref) for x in os.listdir(_dir) if not
+	    created_by_ref) for x in sorted(os.listdir(_dir)) if not
 	    os.path.isdir(os.path.join(_dir, x)) ]
 
 def get_objstore(options):
@@ -820,6 +821,26 @@ def cmd_dump(options):
 	for i in objstr:
 		print(i.encode('json'))
 
+def cmd_auto(options):
+	for i in options.files:
+		mf = magic.detect_from_filename(i)
+
+		primary = mf[0].split('/', 1)[0]
+		mt = mf[0]
+		if primary == 'text':
+			mt += '; charset=%s' % mf[1]
+
+		print('Set:')
+		print('\tmimetype:\t%s' % mt)
+		print()
+		print('Apply (y/N)?')
+
+		inp = sys.stdin.readline()
+
+		if inp.strip().lower() in ('y', 'yes'):
+			options.modtagvalues = [ '+mimetype=%s' % mt ]
+			cmd_modify(options)
+
 def cmd_list(options):
 	persona, objstr = get_objstore(options)
 
@@ -837,7 +858,6 @@ def cmd_list(options):
 			except (FileNotFoundError, KeyError) as e:
 				print('ERROR: file not found: %s' % repr(i), file=sys.stderr)
 				sys.exit(1)
-
 		except FileNotFoundError:
 			# XXX - tell the difference?
 			print('ERROR: file not found: %s' % repr(i),
@@ -912,6 +932,11 @@ def main():
 	    help='files to modify')
 	parser_mod.set_defaults(func=cmd_modify)
 
+	parser_auto = subparsers.add_parser('auto', help='automatic detection of file properties')
+	parser_auto.add_argument('files', nargs='+',
+	    help='files to modify')
+	parser_auto.set_defaults(func=cmd_auto)
+
 	parser_list = subparsers.add_parser('list', help='list tags on file(s)')
 	parser_list.add_argument('files', nargs='+',
 	    help='files to modify')
@@ -1141,7 +1166,7 @@ class _TestCases(unittest.TestCase):
 
 	def test_enumeratedir(self):
 		files = enumeratedir(self.tempdir, self.created_by_ref)
-		ftest = files[1]
+		ftest = [ x for x in files if x.filename == 'test.txt' ][0]
 		fname = 'test.txt'
 
 		# make sure that they are of type MDBase
@@ -1459,6 +1484,7 @@ class _TestCases(unittest.TestCase):
 					self.assertRegex(stdout.getvalue(), outre)
 				else:
 					self.assertEqual(stdout.getvalue(), cmd.get('stdout', ''))
+
 				self.assertEqual(stderr.getvalue(), cmd.get('stderr', ''))
 
 				self.assertEqual(cm.exception.code, cmd.get('exit', 0))
@@ -1468,9 +1494,13 @@ class _TestCases(unittest.TestCase):
 			i.stop()
 
 	def test_cmds(self):
-		cmds = self.fixtures.glob('cmd.*.json')
+		cmds = sorted(self.fixtures.glob('cmd.*.json'))
 
 		for i in cmds:
+			# make sure each file starts with a clean slate
+			self.tearDown()
+			self.setUp()
+
 			os.chdir(self.tempdir)
 			self.run_command_file(i)
 
diff --git a/ui/setup.py b/ui/setup.py
index dd5590f..4d069ae 100644
--- a/ui/setup.py
+++ b/ui/setup.py
@@ -28,6 +28,7 @@ setup(
         'hypercorn', # option, for server only?
         'orm',
 	'pasn1 @ git+https://www.funkthat.com/gitea/jmg/pasn1.git@c6c64510b42292557ace2b77272eb32cb647399d#egg=pasn1',
+	'file-magic @ git+https://github.com/file/file.git#egg=file-magic&subdirectory=python',
         'pydantic[dotenv]',
     ],
     extras_require = {