flatpak remote-ls flathub | grep org.gtk.Gtk3theme
Here is what the above code is Doing:
1. It’s using the flatpak command to list all the remotes.
2. It’s using grep to filter the output of the previous command to only show the lines that contain the string org.gtk.Gtk3theme.
3. It’s using the pipe (|) to send the output of the previous command to the next command.