I deployed a web page using Apache2 installed on my Ubuntu 17 Azure server. 

Is there a command I can run from the terminal where I can capture a screenshot for my website through the port 80?

I tried this command: `gnome-screenshot` but since it is a server it says: 

```
Unable to init server: Could not connect: Connection refused

(gnome-screenshot:55421): Gtk-WARNING **: cannot open display: 

```

How can I add the port number to this command or how can I tell the command to get the screenshot from my web page ?