xdg-mime: add page (#4998)

pages/linux/xdg-mime.md

@@ -0,0 +1,20 @@
+# xdg-mime
+
+> Query and manage MIME types according to the XDG standard.
+> More information: <https://portland.freedesktop.org/doc/xdg-mime.html>.
+
+- Display the MIME type of a file:
+
+`xdg-mime query filetype {{path/to/file}}`
+
+- Display the default application for opening PNG images:
+
+`xdg-mime query default {{image/png}}`
+
+- Display the default application for opening a specific file:
+
+`xdg-mime query default $(xdg-mime query filetype {{path/to/file}})`
+
+- Set imv as the default application for opening PNG and JPEG images:
+
+`xdg-mime default {{imv.desktop}} {{image/png}} {{image/jpeg}}`