sleep 1 & jobs | wc -l
sleep 1 & x=$(jobs -p); [ "$x" = "$!" ] && echo same
sleep 1 & (jobs); echo .
echo a; return; echo b
x=$(echo e >&2; echo v) 2>/dev/null; echo "[$x]"
mkdir a b; cd a b; echo "st=$?"
echo hi 10>/dev/null
mkdir -p .h; echo .*
case b in [^a]) echo neg;; *) echo lit;; esac
n=HOME; unset $n; cd; echo st=$?
