> 
> If you go in this direction, there is an alternative to what Ben wrote: Use the sequencer to start a run.
> The sequencer script can obtain a new run number from a central instance (e.g. by calling a shell script 
> like 'curl ...' to obtain the new run number, then put it into /Runinfo/Run number as Ben wrote. This has
> the advantage that the run is _started_ already with the correct number, so the history system is fine.
> 

Hi Stefan, this sounds like a perfect solution - thanks! - and leads to another, more technical, question:

- how does one communicate with an external shell script from MSL ? I looked at the MIDAS Sequencer page 
  
  https://daq00.triumf.ca/MidasWiki/index.php/Sequencer

  and didn't find an immediately obvious candidate among the MSL commands. 
  The closest seems to be 

  'SCRIPT script [, a, b, c, ...]' 

  but I couldn't easily figure how to propagate the output of the script back to MIDAS. 
  Let say, the script creates an ASCII file with the next run number. What is the easiest 
  way to import the run number into ODB? - Should an external script spawn a [short-lived] 
  MIDAS client ?  - That would work, but I'm almost sure there is a more straightforward solution. 

  Of course, the assumption that the 'SCRIPT' command provides the solution could be wrong.

-- thanks again, regards, Pasha