On Linux systems icons run all installed programs are in the file system at: /usr/share/applications. And the default program is "Keyboard", where in a separate tab are the hotkeys that are already assigned, and there is the possibility granted to the user, to reassign or appoint their own Custom shortcuts.
Need to open Keyboard app: System Settings=>Keyboard=>Shortcuts=>Custom Shortcuts and click on the button to Add custom shortcuts (in Linux Mint):
Additional window will open with two fields: Name and Command.
These fields must be correctly filled in. In order not to make mistakes in filling the fields and the subsequent opening of the assigned program through the hotkeys.
Open the file manager at /usr/share/applications (as I wrote in the beginning of the article, where are all the icons start applications installed in your system), right click on the program icon and in the opened context menu select Properties (example):
In the Properties window we are interested in the fields - Name and Command:
Note. Just specify that field Name is not so important for correct filling, because the name or the program name, in this case, carries purely informative function for you, as the user, and the command to open the program system.
So, copy the command from the field Command and paste it in the opened window hotkeys:
And then displays the string in an Custom shortcuts with the name of the program to run.
Now click below: on the string is not assigned, and press the keyboard shortcut/key that will open the program (in Linux Mint):
May the force be with you