Enable loading variable contents from a file

[simonsabin]

It is often needed to pass teh contents of a file to a script in SQLCMD. Multi line variables are not possible and also prone to problems.

If would be good to have something like -vf CERTDATA=c:\mycert.cert which would then pass the contents of the file as a variable.

Whilst in your shell of choice you could read contents and pass it, the challenge is that you have to escape the contents to ensure it is parsed correctly.