Useful ubuntu commands

This is quick list of useful ubuntu related commands to fix certain problems

Display issues

Getting Gtk-WARNING **: cannot open display:

Enter xhost +

Happens when root programs (e.g. software managers) are trying to use your session

x2go on Ubuntu Mate

Big problems here, but it does work with fiddling (Jun 2017) - not sure how much of this is require;

• First add this (and create) to your ~/.profile

export GSETTINGS_SCHEMA_DIR=/usr/share/gconf/schemas/:/usr/share/mate:/usr/share/mate:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop 
export XDG_DATA_DIRS=/usr/share/gconf/schemas/:/usr/share/mate:/usr/share/mate:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop

• I then had to create a new custom session for me to log in locally and use Mate for x2go - I did this by creating a ~/.xinitrc file, making it executable and adding;

#!/usr/bin/env bash
unset DBUS_SESSION_BUS_ADDRESS &
# redirect to /dev/null due to x2go bug 914
dbus-launch /usr/bin/mate-session > /dev/null

• Then linking to .xsessions (ln -s ~/.xinitrc ~/.xsession)

• And creating a new custom file in xsessions folder /usr/share/xsessions/custom.desktop with;

[Desktop Entry]
Name=Xsession
Exec=/etc/X11/Xsession

• You then need to log in to this custom session on your pc and use x2go to login using Mate environment. I'm sure there's a way of reusing the custom session in x2go, but so far, I can't get it to work (I've tried just startx which calls ~/.xinitrc directly).