Requesting to elaborate some parameters

[Antonynixson]

On the example https://github.com/xenserverarmy/packer/blob/master/examples/centos-7.json

could you please explain the purpose of the below parameter you've used.??

especially the use of the below,

1. boot_command
2. http_directory
3. script_url
4. nfs_mount
5. shutdown_command

What this will do boot_command ??

"boot_command": [
        "<tab><end> ks=http://10.204.137.80/ks/centos7-ks.cfg<enter><wait>"
      ]

What this will do http_directory ??

"http_directory": "/var/www/html/packer"

What this will do script_url ??

"script_url": "http://10.204.137.80/packer/xenserver/"

What this will do nfs_mount ??

"nfs_mount": "10.204.136.41:/vol/exports/packer"

The reason why anything not specified in shutdown_command ??

"shutdown_command": "",

Also could you please explain https://github.com/xenserverarmy/packer/blob/master/scripts/copyiso.sh
copyiso.sh script what it will do ?