wkhtmltopdf on ubuntu headless

Install wkhtmltopdf with

sudo apt-get update
sudo apt-get install wkhtmltopdf

Then try to run it, as per the example at http://wkhtmltopdf.org

wkhtmltopdf http://google.com google.pdf

Receive this error:

QXcbConnection: Could not connect to display
Aborted (core dumped)

Or -- as happened on a different day on a different machine, with a problem that had the exact same solution -- I got this error:

$ wkhtmltopdf http://google.com google.pdf

wkhtmltopdf: cannot connect to X server

The problem in both cases is that there's no desktop environment, no display, no X server.

The solution, according to http://unix.stackexchange.com/questions/192642/wkhtmltopdf-qxcbconnection-could-not-connect-to-display

There is a more easy way to make John WH Smith solution.

Just install xvfb from apt and then, you can run:

xvfb-run wkhtmltopdf

i.e., just put xvfb-run before any wkhtmltopdf command.)

Okay so I ran:

sudo apt-get update
sudo apt-get install xvfb

Then the command worked:

$ xvfb-run wkhtmltopdf http://google.com google.pdf
Loading page (1/2)
Printing pages (2/2)

(meanwhile i have a similar blocking issue with wkhtmltopdf on windows... it hangs the process... but do not yet have a solution.)