mount_share () {

    mkdir /data
    echo //$STORAGE_NAME.file.core.windows.net/$STORAGE_SHARE /data cifs vers=3.0,username=$STORAGE_NAME,password=$STORAGE_KEY,dir_mode=0755,file_mode=0644,serverino >> /etc/fstab
    mount -a

}

root@xx255rs2sptry000001:~# STORAGE_NAME=ggg
root@xx255rs2sptry000001:~# STORAGE_KEY=sakey
root@xx255rs2sptry000001:~# STORAGE_SHARE=sashare
root@xx255rs2sptry000001:~# echo //$STORAGE_NAME.file.core.windows.net/$STORAGE_SHARE /data cifs vers=3.0,username=$STORAGE_NAME,password=$STORAGE_KEY,dir_mode=0755,file_mode=0644,serverino >> /etc/fstab
root@xx255rs2sptry000001:~# cat /etc/fstab
# CLOUD_IMG: This file was created/modified by the Cloud Image build process
UUID=e990f8b3-1d6b-4615-8280-8ead4ed2fe7c       /        ext4   defaults,discard        0 0

# CLOUD_IMG: This file was created/modified by the Cloud Image build process
# The following is used to dynamically configured additional
# NICs. Do not remove unless you know what you are doing.
none /etc/network/interfaces.dynamic.d tmpfs   nodev,noexec,nosuid,size=64K 0 0
/dev/disk/cloud/azure_resource-part1    /mnt    auto    defaults,nofail,x-systemd.requires=cloud-init.service,comment=cloudconfig       0       2
//ggg.file.core.windows.net/sashare /data cifs vers=3.0,username=ggg,password=sakey,dir_mode=0755,file_mode=0644,serverino
root@xx255rs2sptry000001:~# mount -a
mount: /etc/fstab: parse error: ignore entry at line 9.