> - how does one communicate with an external shell script from MSL ? 

trying to answer my own question, as I didn't find a clear answer in the forum archive :

1. one could have a MSL script with a 'SCRIPT ./myscript.sh' command in it - 
   that would run a shell script named 'myscript.sh'
   [that was not obvious from the documentation on MIDAS wiki, and adding a couple of clarifying 
    sentences there would go long ways]

2. if a script produces an ascii file with a known name, for example, 'a.odb', with the following two lines:

--------------------------------------- a.odb
[/Runinfo]
Run number  = INT32 : 105
--------------------------------------- end a.odb

one can use the 'odbload' MSL command :

odbload a.odb

and get the run number set to 105. It works, but I'm curious if that is the right (envisaged) 
way of interacting with the shell scripts, or one could do better than that.

-- thanks, regards, Pasha