remove unnecessary unmap procedure.
Merge pull request #47 from wakameci/remove-unnecessary-unmap-procedure

remove unnecessary unmap procedure.
use if-statement.
Merge pull request #48 from wakameci/remove-unnecessary-unmap-procedure

use if-statement.
make sure to update bash.
Merge pull request #49 from wakameci/anti-shellshock

make sure to update bash.