In Linux Mint 17, when I try to open Synaptic Package Manager or Software Manager from the gui, the popup appears to enter my password. Yet when I enter it correctly, nothing happens; neither window opens. When I run synaptic from terminal, this is the output:
user@hostname ~ $ sudo synaptic [sudo] password for user: No protocol specified ** (synaptic:4516): WARNING **: Could not open X display No protocol specified error: XDG_RUNTIME_DIR not set in the environment. (synaptic:4516): Gtk-WARNING **: cannot open display: :0
Does anybody know how I could fix this?