Fix tests to work on Ubuntu (dash)

The system shell (/bin/sh) on Ubuntu is dash, which aims to be a
POSIX standard shell.  In particular, dash does not implement any
of the common extensions to the standard that, say, bash and ksh
do.

Replace some non-POSIX constructs in setup.sh with more portable
and mundane code.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>