I was trying to edit my
sources.list in order to add local mirror information. I am not comfortable with command line editors, so I tried using
sudo mousepad /etc/apt/sources.list.
I got the following error report.
No protocol specified (mousepad:4942): Mousepad-ERROR **: Cannot open display:
I tried several other editors such as gedit, kwrite etc. but I get similar error reports.
No protocol specified ** (gedit:4957): WARNING **: Could not open X display No protocol specified Unable to init server: Could not connect: Connection refused (gedit:4957): Gtk-WARNING **: cannot open display: :0
I am on a local 64 bit system running Debian Jessie.