This is actually the correct behavior. 
 
The part of the command after the pipe ("read", in this case) is executed in a 
different process space, so the variable isn't available to the originally 
calling shell. 
 
You _can_ do: 
 
whatever |while read a; do echo $a; done 
 
(because the echo is in the same process space as the read) 
 
You _can't_ do: 
whatever |read a 
echo $a 
 
(because the echo is in the same process space as "whatever", but not as 
"read"). 
 
Similarily: 
 
echo foo |read a && echo $a 
 
Won't work, but 
 
echo foo |(read a && echo $a) 
 
will. 

Yes, fair enough.  This is the difference between sh and ksh is it not, that 
ksh spawns children differently, so echo hello | read line will work because it 
passes it's environment down differently.  I assume that bash behaves like sh 
because it is a bourne again shell not a bourne again korn shell ;-)

My problem was that I was porting a shell script from a Sequent (ksh) to a 
linux machine (bash) and found that the command I had been using for years 
didn't work.  I have just revamped the script a bit and all is well.

(Mind you - I've just noticed that it doesn't work in the RH7.2 ksh either - it 
does in the PTX and SOlaris 5.8 ksh's)

Anyway, thanks for the explanation and your help.

David