Parallel in linux

http://www.gnu.org/software/parallel/man.html#differences_between_gnu_parallel_and_alternatives

http://tldp.org/LDP/abs/html/subshells.html

(
# Inside parentheses, and therefore a subshell . . .
while [ 1 ]   # Endless loop.
do
  echo "Subshell running . . ."
done
)