title: Add a "shell-local" post-processor but run many times
body: <p>I'm using Packer 0.9.0 and as post-processor "shell-local" to run one script. The problem is that the shell script run for each artifacts generated (.vmdk, .vmx, etc.) and I don't know the reason.</p>
  
  <p>The source code:</p>
  
  <pre class="lang-json prettyprint-override"><code>{
      "variables": {
          "root_password": "pass",
          "output_directory": "output/centos6-aufs-master-slave-vmw"
      },
      "builders": [
          {
              "type": "vmware-iso",
              "name": "centos6-aufs-master-slave-vmw",
  
              "iso_url": "http://myrepo/software/isos/CentOS-6.5-x86_64-minimal.iso",
              "iso_checksum": "ee3c7e96ad0a33d8af787acbf6d54e56",
              "iso_checksum_type": "md5",
  
              "ssh_username": "root",
              "ssh_password": "{{user `root_password`}}",
              "ssh_port": 22,
              "ssh_wait_timeout": "10000s",
  
              "shutdown_command": "shutdown -P now",
              "boot_command": [
                  "&lt;tab&gt; text ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/al-master-slave-ks.cfg&lt;enter&gt;&lt;wait&gt;"
              ],
  
              "boot_wait": "10s",
  
              "disk_size": 51200,
              "disk_type_id": "0",
  
              "format": "ovf",
  
              "guest_os_type": "rhel6-64",
              "tools_upload_flavor": "linux",
  
              "http_directory": "http",
  
              "output_directory": "{{user `output_directory`}}",
  
              "vmx_data": {
                  "memsize": "2048",
                  "numvcpus": "1",
                  "cpuid.coresPerSocket": "1"
              }
          }
      ],
      "post-processors": [
          {
              "type": "shell-local",
              "only": ["centos6-aufs-master-slave"],
              "inline": ["cd scripts","./vmx-to-ova.sh"],
              "environment_vars": ["PACKER_OUTPUT_DIRECTORY=/home/myuser/projects/IT/packer-project/output/centos6-aufs-master-slave-vmw"]
          }
      ]
  }
  </code></pre>