packer-cn/website/pages/docs/provisioners/shell-local.mdx

---
description: |
  shell-local will run a shell script of your choosing on the machine where
  Packer is being run - in other words, shell-local will run the shell script on
  your build server, or your desktop, etc., rather than the remote/guest machine
  being provisioned by Packer.
layout: docs
page_title: Shell (Local) - Provisioners
sidebar_title: Shell (Local)
---

# Local Shell Provisioner

Type: `shell-local`

shell-local will run a shell script of your choosing on the machine where
Packer is being run - in other words, shell-local will run the shell script on
your build server, or your desktop, etc., rather than the remote/guest machine
being provisioned by Packer.

The [remote shell](/docs/provisioners/shell) provisioner executes shell
scripts on a remote machine.

## Basic Example

The example below is fully functional.

```json
{
  "type": "shell-local",
  "command": "echo foo"
}
```

## Configuration Reference

The reference of available configuration options is listed below. The only
required element is "command".

Exactly _one_ of the following is required:

- `command` (string) - This is a single command to execute. It will be
  written to a temporary file and run using the `execute_command` call below.
  If you are building a windows vm on AWS, Azure, Google Compute, or OpenStack
  and would like to access the generated password that Packer uses to connect
  to the instance via WinRM, you can use the template variable `{{.WinRMPassword}}`
  to set this as an environment variable.

- `inline` (array of strings) - This is an array of commands to execute. The
  commands are concatenated by newlines and turned into a single file, so
  they are all executed within the same context. This allows you to change
  directories in one command and use something in the directory in the next
  and so on. Inline scripts are the easiest way to pull off simple tasks
  within the machine in which packer is running.

- `script` (string) - The path to a script to execute. This path can be
  absolute or relative. If it is relative, it is relative to the working
  directory when Packer is executed.

- `scripts` (array of strings) - An array of scripts to execute. The scripts
  will be executed in the order specified. Each script is executed in
  isolation, so state such as variables from one script won't carry on to the
  next.

Optional parameters:

- `environment_vars` (array of strings) - An array of key/value pairs to
  inject prior to the `execute_command`. The format should be `key=value`.
  Packer injects some environmental variables by default into the
  environment, as well, which are covered in the section below. If you are
  building a windows vm on AWS, Azure, Google Compute, or OpenStack and would
  like to access the generated password that Packer uses to connect to the
  instance via WinRM, you can use the template variable `{{.WinRMPassword}}`
  to set this as an environment variable. For example:
  `"environment_vars": "WINRMPASS={{.WinRMPassword}}"`

- `env_var_format` (string) - When we parse the environment_vars that you
  provide, this gives us a string template to use in order to make sure that
  we are setting the environment vars correctly. By default on Windows hosts
  this format is `set %s=%s &&` and on Unix, it is `%s='%s'`. You probably
  won't need to change this format, but you can see usage examples for where
  it is necessary below.

- `execute_command` (array of strings) - The command used to execute the
  script. By default this is `["/bin/sh", "-c", "{{.Vars}}", "{{.Script}}"]`
  on unix and `["cmd", "/c", "{{.Vars}}", "{{.Script}}"]` on windows. This is
  treated as a [template engine](/docs/templates/engine). There are two
  available variables: `Script`, which is the path to the script to run, and
  `Vars`, which is the list of `environment_vars`, if configured.

  If you choose to set this option, make sure that the first element in the
  array is the shell program you want to use (for example, "sh"), and a later
  element in the array must be `{{.Script}}`.

  This option provides you a great deal of flexibility. You may choose to
  provide your own shell program, for example "/usr/local/bin/zsh" or even
  "powershell.exe". However, with great power comes great responsibility -
  these commands are not officially supported and things like environment
  variables may not work if you use a different shell than the default.

  For backwards compatibility, you may also use `{{.Command}}`, but it is
  decoded the same way as `{{.Script}}`. We recommend using `{{.Script}}` for the
  sake of clarity, as even when you set only a single `command` to run,
  Packer writes it to a temporary file and then runs it as a script.

  If you are building a windows vm on AWS, Azure, Google Compute, or OpenStack
  and would like to access the generated password that Packer uses to connect
  to the instance via WinRM, you can use the template variable `{{.WinRMPassword}}`
  to set this as an environment variable.

- `inline_shebang` (string) - The
  [shebang](http://en.wikipedia.org/wiki/Shebang_%28Unix%29) value to use
  when running commands specified by `inline`. By default, this is
  `/bin/sh -e`. If you're not using `inline`, then this configuration has no
  effect. **Important:** If you customize this, be sure to include something
  like the `-e` flag, otherwise individual steps failing won't fail the
  provisioner.

- `only_on` (array of strings) - This is an array of [runtime operating
  systems](https://golang.org/doc/install/source#environment) where
  `shell-local` will execute. This allows you to execute `shell-local` _only_
  on specific operating systems. By default, shell-local will always run if
  `only_on` is not set."

- `use_linux_pathing` (bool) - This is only relevant to windows hosts. If you
  are running Packer in a Windows environment with the Windows Subsystem for
  Linux feature enabled, and would like to invoke a bash script rather than
  invoking a Cmd script, you'll need to set this flag to true; it tells
  Packer to use the linux subsystem path for your script rather than the
  Windows path. (e.g. /mnt/c/path/to/your/file instead of
  C:/path/to/your/file). Please see the example below for more guidance on
  how to use this feature. If you are not on a Windows host, or you do not
  intend to use the shell-local provisioner to run a bash script, please
  ignore this option.

- `valid_exit_codes` (list of ints) - Valid exit codes for the script. By
  default this is just 0.

@include 'provisioners/common-config.mdx'

## Execute Command

To many new users, the `execute_command` is puzzling. However, it provides an
important function: customization of how the command is executed. The most
common use case for this is dealing with **sudo password prompts**. You may
also need to customize this if you use a non-POSIX shell, such as `tcsh` on
FreeBSD.

### The Windows Linux Subsystem

The shell-local provisioner was designed with the idea of allowing you to run
commands in your local operating system's native shell. For Windows, we've
assumed in our defaults that this is Cmd. However, it is possible to run a bash
script as part of the Windows Linux Subsystem from the shell-local provisioner,
by modifying the `execute_command` and the `use_linux_pathing` options in the
provisioner config.

The example below is a fully functional test config.

One limitation of this offering is that "inline" and "command" options are not
available to you; please limit yourself to using the "script" or "scripts"
options instead.

Please note that the WSL is a beta feature, and this tool is not guaranteed to
work as you expect it to.

    {
        "builders": [
          {
            "type":         "null",
            "communicator": "none"
          }
        ],
        "provisioners": [
          {
              "type": "shell-local",
              "environment_vars": ["PROVISIONERTEST=ProvisionerTest1"],
              "execute_command": ["bash", "-c", "{{.Vars}} {{.Script}}"],
              "use_linux_pathing": true,
              "scripts": ["C:/Users/me/scripts/example_bash.sh"]
          },
          {
              "type": "shell-local",
              "environment_vars": ["PROVISIONERTEST=ProvisionerTest2"],
              "execute_command": ["bash", "-c", "{{.Vars}} {{.Script}}"],
              "use_linux_pathing": true,
              "script": "C:/Users/me/scripts/example_bash.sh"
          }
      ]
    }

## Default Environmental Variables

In addition to being able to specify custom environmental variables using the
`environment_vars` configuration, the provisioner automatically defines certain
commonly useful environmental variables:

- `PACKER_BUILD_NAME` is set to the name of the build that Packer is running.
  This is most useful when Packer is making multiple builds and you want to
  distinguish them slightly from a common provisioning script.

- `PACKER_BUILDER_TYPE` is the type of the builder that was used to create
  the machine that the script is running on. This is useful if you want to
  run only certain parts of the script on systems built with certain
  builders.

- `PACKER_HTTP_ADDR` If using a builder that provides an http server for file
  transfer (such as hyperv, parallels, qemu, virtualbox, and vmware), this
  will be set to the address. You can use this address in your provisioner to
  download large files over http. This may be useful if you're experiencing
  slower speeds using the default file provisioner. A file provisioner using
  the `winrm` communicator may experience these types of difficulties.

## Safely Writing A Script

Whether you use the `inline` option, or pass it a direct `script` or `scripts`,
it is important to understand a few things about how the shell-local
provisioner works to run it safely and easily. This understanding will save you
much time in the process.

### Once Per Builder

The `shell-local` script(s) you pass are run once per builder. That means that
if you have an `amazon-ebs` builder and a `docker` builder, your script will be
run twice. If you have 3 builders, it will run 3 times, once for each builder.

### Always Exit Intentionally

If any provisioner fails, the `packer build` stops and all interim artifacts
are cleaned up.

For a shell script, that means the script **must** exit with a zero code. You
_must_ be extra careful to `exit 0` when necessary.

## Usage Examples:

### Windows Host

Example of running a .cmd file on windows:

          {
              "type": "shell-local",
              "environment_vars": ["SHELLLOCALTEST=ShellTest1"],
              "scripts": ["./scripts/test_cmd.cmd"]
          }

Contents of "test_cmd.cmd":

    echo %SHELLLOCALTEST%

Example of running an inline command on windows: Required customization:
tempfile_extension

          {
              "type": "shell-local",
              "environment_vars": ["SHELLLOCALTEST=ShellTest2"],
              "tempfile_extension": ".cmd",
              "inline": ["echo %SHELLLOCALTEST%"]
          }

Example of running a bash command on windows using WSL: Required
customizations: use_linux_pathing and execute_command

          {
              "type": "shell-local",
              "environment_vars": ["SHELLLOCALTEST=ShellTest3"],
              "execute_command": ["bash", "-c", "{{.Vars}} {{.Script}}"],
              "use_linux_pathing": true,
              "script": "./scripts/example_bash.sh"
          }

Contents of "example_bash.sh":

    #!/bin/bash
    echo $SHELLLOCALTEST

Example of running a powershell script on windows: Required customizations:
env_var_format and execute_command

          {
              "type": "shell-local",
              "environment_vars": ["SHELLLOCALTEST=ShellTest4"],
              "execute_command": ["powershell.exe", "{{.Vars}} {{.Script}}"],
              "env_var_format": "$env:%s=\"%s\"; ",
              "script": "./scripts/example_ps.ps1"
          }

Example of running a powershell script on windows as "inline": Required
customizations: env_var_format, tempfile_extension, and execute_command

          {
              "type": "shell-local",
              "tempfile_extension": ".ps1",
              "environment_vars": ["SHELLLOCALTEST=ShellTest5"],
              "execute_command": ["powershell.exe", "{{.Vars}} {{.Script}}"],
              "env_var_format": "$env:%s=\"%s\"; ",
              "inline": ["write-output $env:SHELLLOCALTEST"]
          }

### Unix Host

Example of running a bash script on unix:

          {
              "type": "shell-local",
              "environment_vars": ["PROVISIONERTEST=ProvisionerTest1"],
              "scripts": ["./scripts/example_bash.sh"]
          }

Example of running a bash "inline" on unix:

          {
              "type": "shell-local",
              "environment_vars": ["PROVISIONERTEST=ProvisionerTest2"],
              "inline": ["echo hello",
                         "echo $PROVISIONERTEST"]
          }

Example of running a python script on unix:

          {
              "type": "shell-local",
              "script": "hello.py",
              "environment_vars": ["HELLO_USER=packeruser"],
              "execute_command": ["/bin/sh", "-c", "{{.Vars}} /usr/local/bin/python {{.Script}}"]
          }

Where "hello.py" contains:

    import os

    print('Hello, %s!' % os.getenv("HELLO_USER"))