On 27/08/2012 14:33, Jonathan Gibbons wrote:
Alan, The expression as written does not need $PS because the syntax being used is ${A:-${B}} where the :- is shell syntax for providing a default if not set. If I had suggested ${A}:${B} then $PS would be more appropriate.
Okay, I was mis-reading it, in which case what you have looks fine. -Alan