How to register an AppImage as a desktop application in Linux

The Scenario:
You have an .AppImage file and would like to treat it like an installed Linux app.

The solution:
Create a custom .desktop file

For this article, I'll use the following constraints:

• Register the Electron.js app Marktext on an Ubuntu 20.04 distro
• Use this icon from icon-library.com

Let's do it.

NOTE: You might have to use sudo commands to access files in the /bin and /usr directories

1. Download the .AppImage file and an icon you would like to register it with
2. Move the .AppImage file to the path /bin,
   e.g. sudo mv ~/Downloads/Marktext.AppImage /bin/
3. Make it executable with sudo chmod +x /bin/Marktext.AppImage
4. Save the icon under /usr/share/icons/custom/markdown.png
   e.g. sudo mkdir --parents /usr/share/icons/custom && sudo mv ~/Downloads/markdown.png /usr/share/icons/custom/
5. Create a .desktop file under ~/.local/share/applications/marktext.desktop
6. Paste the following content into it (make sure to remove the comments):

[Desktop Entry]
Name=Mark Text
Comment=Next generation markdown editor
Exec=/bin/marktext-x86_64.AppImage        # replace with your .AppImage
Terminal=false
Type=Application
Icon=/usr/share/icons/custom/markdown.png # replace with your icon
Categories=Office;TextEditor;Utility;
MimeType=text/markdown;
Keywords=marktext;markdown;               # add searchable keywords
StartupWMClass=marktext
Actions=NewWindow;

That should do it. Try pressing the Super key now and search for the app.

Hitting enter should then start up your application.