mime: added entry

wiki/linux/mime.md

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+# MIME
+
+A MIME type (short for Multipurpose Internet Mail Extensions) is a identifier
+for file formats and contents on the internet.
+
+## Setting applications for MIME types
+
+In `~/.config/mimeapps.list` a list of applications to run specific MIME
+types can be found.
+An example file looks like the following:
+
+```txt
+[Default Applications]
+text/x-shellscript=text.desktop;
+x-scheme-handler/magnet=torrent.desktop;
+application/x-bittorrent=torrent.desktop;
+x-scheme-handler/mailto=mail.desktop;
+text/plain=text.desktop;
+application/postscript=pdf.desktop;
+application/pdf=pdf.desktop;
+image/png=img.desktop;
+image/jpeg=img.desktop;
+image/gif=img.desktop;
+application/rss+xml=rss.desktop
+video/x-matroska=video.desktop
+inode/directory=file.desktop
+```
+
+A line consists of a MIME type left of the equals sign and an application on
+the right of it.
+The application can be found in `~/.local/share/applications/`.
+In this directory a file for every application on the right side of the equals
+sign with the same title can be found.
+
+A simple application file looks like the following example of `img.desktop`:
+
+```txt
+[Desktop Entry]
+Type=Application
+Name=Image viewer
+Exec=/usr/bin/sxiv -a %f
+```
+
+Atleast `Type`, `Name` and `Exec` have to be specified for a minimal
+application file.
+
+## Getting MIME type of a file
+
+The MIME type of a file can be returned by running
+`xdg-mime query filetype <file>` or `file -b --mime-type image.png`.
+The MIME type can be then used to set default applications as explained in
+[the section regarding setting applications for MIME types](#setting-applications-for-mime-types).