Question: How can I take a screenshot in X.org?

I am unsure if the Print Screen button will "just work" and I don't know how I would go about testing it.

Answer: 
The most commonly used Linux application for taking screen-shots is called `scrot`

You can install it with for Debian:

`sudo apt-get install scrot`

Or for Arch:

`sudo pacman -S scrot`

A screenshot is taken by typing:

`scrot output-file.png`

If you want to bind `scrot` to the `print screen` key then that will need to be controlled by your window manager.
This is the perl6 script I use to take ***root area window*** or ***delay*** ScreenShots using import: 

```
#!/usr/bin/env perl6
use v6;

sub message(Str $file) {
  run <xmessage -nearmouse -timeout 3>, "Screenshot saved in $file";
}

sub print_window(Str $file) {
  qx{xprop -root | grep "_NET_ACTIVE_WINDOW(WINDOW)"} ~~ /(0x\d*).*$/;
  run <import -window>, $0, $file;
  message($file);
}

sub MAIN( Str $option where $option ∈ <root area window delay> ) {
  my $today = DateTime.now( formatter => { 
        sprintf "%04d_%02d_%02d_%02d:%02d:%02d", 
                .year, .month, .day, .hour, .minute, .second 
       } );
  my $file  = "$*HOME/Dades/Imatges/ScreenShots/$today.png";

  given $option {
    when 'root'   { run <import -window root>, $file; message($file) }
    when 'area'   { run "import", $file             ; message($file) }
    when 'window' { print_window($file)                              }
    when 'delay'  { sleep 5; print_window($file)                     }
    default       { say 'Something went wrong'      ; exit           }
  }
}

```

These are the key bindings in i3 to run the script:

```
bindsym $mod+Print exec Print_Screen root 
bindsym --release $mod+Shift+Print exec Print_Screen area
bindsym $mod+Mod1+Print exec Print_Screen delay
bindsym $mod+Control+Print exec Print_Screen window

```