packer/provisioner/shell/test-fixtures/shell-provisioner.txt

{
  "type": "shell",
  "inline": [
    "echo {{ build `ID`}} > provisioner.{{ build `PackerRunUUID`}}.txt"
  ]
},
{
    "type": "file",
    "source": "provisioner.{{ build `PackerRunUUID`}}.txt",
    "destination": "provisioner.shell.{{ build `PackerRunUUID`}}.txt",
    "direction": "download"
}