You can use dconf
to manipulate gnome shortcuts from terminal.
For example this lists where gnome saves its screenshots
dconf dump /org/gnome/gnome-screenshot/
dconf dump /
dconf dump /org/gnome/settings-daemon/plugins/media-keys/custom-keybindings/custom1/
dconf read /org/gnome/settings-daemon/plugins/media-keys/custom-keybindings/custom1/binding
dconf write /org/gnome/settings-daemon/plugins/media-keys/custom-keybindings/custom1/binding "'<Super>c'"