I'm running Firefox on a Xvfb in a VPS. What I want to do is to take a full page screenshot of the page.
I can redirect Firefox to particular page using
import root -window output.jpg
Since Firefox 16 you can press shift-F2 or go to Tools > Web Developer > Developer Toolbar to open a command line. Write:
and press Intro in order to take a screeshot.
To fully answer the question, you can even save the whole page, not only the visible part of it:
And to copy the screenshot to clipboard, use
screenshot --clipboard --fullpage
Firefox 18 changes the way arguments are passed to commands, you have to add "--" before them.
You can find some documentation and the full list of commands here.
PS. The screenshots are saved into the downloads directory by default.