Fix evaluation on MacOSX

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Quote the script before eval'ing it

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Support MacOSX & Linux

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>