Mirror display on Ubuntu 18.04

I can't get into mirror display trying to connect external Dell monitor and the laptop connects as an extended monitor, I can see only part of the background on the external monitor. I'd like to get mirror or able to work on the other monitor. If any one can help me with this?

2 Answers

Unfortunately, I couldn't find the setting from the display settings to make this change, I wanted to mirror displays for pair programming.. Good news is that there is always a terminal solution!

Open a terminal and type xrandr, this will give you a long list of which displays are connected and their resolutions... etc. these are the important lines of it (from my machine)

eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
.
.
.
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 593mm x 371mm

in this case, eDP-1 and DP-2 are the names of my screens. To mirror them, you have to run this command

xrandr --output eDP-1 --output DP-2 --same-as eDP-1

change the names of the displays in that command according to what you get. Your screens will turn black for a second or two then they'll come back up mirrored.

Click on "Show Applications" (the 9 dots at the bottom left of your screen), then select "Settings".

When you have opened Settings, choose "Displays". Then I don't remember exactly what it looks like when you have two displays, but there should be some way to choose that you want to mirror the displays, you choose that in a drop-down list or similar.