My VM's system is centos7，I have configured the hostname and IP address successfully through the cloud-init.

But I dont know how to configure the custom script，Is here anyone can help me？

For example：

      I want to format the disk-sdb，then mount it on /data.

'''

3 steps

mkfs.xfs  /dev/sdb

mount /dev/sdb /data

echo"/dev/sdb /data xfs defaults  0 0" >>/etc/fstab

'''

      How do I write this script?