Ubuntu – Many screenshots within a limited time saved directly, without asking for a filename

Ok, found this for X windows:

FVWM Forums • View topic - Thumbnailing a Window on another Viewport

As to why you can't access a window (that is, take a picture of it when it is not on the same desk/page as the current viewport) is because windows that are not on the current page are unmapped. This is true when one changes pages/desks -- the windows are unmapped, and the windows on the current viewport are remapped.

So, I guess that means what I want is impossible? Although there are two workarounds:

• use xrandr to increase the virtual size of (each of the four) viewports

This is what works for me - first query to see which output you want, then execute:

$ xrandr -q
Screen 0: minimum 320 x 200, current 1024 x 600, maximum 4096 x 4096
LVDS1 connected 1024x600+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x600       60.0*+
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 disconnected (normal left inverted right x axis y axis)

$ xrandr --output LVDS1 --panning 1600x768

... see also X/Config/Resolution - Ubuntu Wiki

• Use xvfb for virtual render

Got this via x11 - Remote offscreen rendering - Server Fault, also see Xvfb - Wikipedia, the free encyclopedia for examples. This is what worked for me - each command goes in own terminal (as some of them are meant to be services)

# start xvfb as display 1 - note the "screen 0" there refers to "its own" screen 0; should set it to 24-bit color

Xvfb :1 -screen 0 1600x1200x24 -pixdepths 3 -fp /usr/share/fonts/X11/Type1

# start metacity on display 1 (would start gdm, but [Bug #598848: gdm no longer works with xvfb](https://bugs.launchpad.net/bugs/598848)
# needed to we have title bars, and possibility to move windows around 

DISPLAY=:1 metacity

# start application (here web-browser arora) again on display 1

DISPLAY=:1 arora

# start vnc server, which will bridge display 1 to port 5900
# note - this command exists, however starts a server in background 

x11vnc -display :1 -bg -nopw -listen localhost -xkb

# start vnc viewer on port 5900 - so we can see display 1:
# note also - when vncviewer exits, it also will kill the x11vnc server

vncviewer -FullColor=1 localhost:5900

The problem here is that not all parts of the OS are initialized - so there are no window decoration, and only basic X fonts; although, apps may find their own fonts, as seen below:

xvfb looks almost ideal to me - since I could basically set up an "invisible" environment, as big as I want, and take screenshots directly from it (using xwd). The problem is that I cannot have a window on "my" DISPLAY=:0, then switch it to the 'virtual' DISPLAY=:1 for screenshotting, then bring it back to DISPLAY=:0. Then one must set up an application specifically for xvfb; and if so happens you need more size - then the whole chain above needs to be restarted.

On the other hand, I find working with 4 workspaces and large viewports (shwere the mouse moves you around within a viewport) a bit confusing - then again, can change the size there on the fly and nothing needs to be restarted; and plus I can use any of the usual screenshot tools (but I'd still have to switch viewports).

Needless to say, I'd still love to hear about a possible command line solution that could do this kind of screenshotting in one go :)