you need bash shell to execute this script.
make you you have provided executable permissions to the script.
make sure you have coreutils.x86_64 package on your server.
RHEL : yum install coreutils.x86_64
DEBIAN : apt-get install coreutils.x86_64
chmod 755 test1.sh
./test1.sh
writes the numbers from 1 - 10 in random order.Each number will appear only once.
No limitations or bugs as of now. please raise a issue if you found any.