I want to run a sudo command that prompts a GUI for the user to enter their password and get the password back for future use.
running this in a gnome-extention
GLib.spawn_command_line_sync('sudo echo e')
I get the following error
sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
You should never be storing user passwords for later use or running privileged programs that spawn other programs, but instead prompting each time you need it.
To prompt for a privileged program, you can usually use pkexec in place of sudo. Additionally you should be spawning asynchronously with Gio.Subprocess whenever possible, as a synchronous subprocess will block the main thread of GNOME Shell.