Ansible modules - win_command vs win_shell

How to automate the execution of PowerShell or cmd.exe code on windows target hosts using Ansible Playbook with win_command and win_shell modules.

April 8, 2022

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Ansible modules - win_command vs win_shell

How to automate the execution of PowerShell or cmd.exe code on windows target hosts using Ansible Playbook with win_command and win_shell modules.

What is the difference between win_command vs win_shell Ansible modules? These two Ansible modules are confused one for another but they’re fundamentally different. Both modules allow you to execute win_command on a target host but in a slightly different way. I’m Luca Berton and welcome to today’s episode of Ansible Pilot.

win_command vs win_shell

win_command
Executes a command on a remote Windows node
it bypasses the Windows shell
always set changed to True
win_shell
Execute shell commands on Windows target hosts
redirections and win_shell’s inbuilt functionality
always set changed to True

The win_command and win_shell Ansible modules execute win_commands on the Windows target node. Generally speaking, is always better to use a specialized Ansible module to execute a task. However, sometimes the only way is to execute a Windows PowerShell or cmd.exe via the win_command or win_shell module. Let me reinforce again, you should avoid as much as possible the usage of win_command/win_shell instead of a better module. Both modules execute PowerShell or cmd.exe commands on Windows target nodes but in a sensible different way. The win_command modules execute win_commands on the target machine without using the target win_shell, it simply executes the win_command. The target win_shell is for example sending any PowerShell or cmd.exe. t will not be processed through the shell, so variables like $env:HOME and operations like "<", ">", "|", and ";" are not available. On the other side, every command executed using the win_shell module has all PowerShell or cmd.exe features so it could be expanded in runtime. From the security point of viewwin_command module is more robust and has a more predictable outcome because it bypasses the shell. Both modules returned always changed status because Ansible is not able to predict if the execution has or has not altered the target system. For non-Windows targets, use the ansible.builtin.command and ansible.builtin.shell modules instead.

win_command

Executes a command on a remote Windows node

The win_command module won’t be impacted by local win_shell variables because it bypasses the win_shell. At the same time, it may not be able to run win_shell built-in features and redirections.

win_shell

Execute shell commands on target hosts

The win_shell Ansible module is potentially more dangerous than the win_command module and should only be used when you actually really need the PowerShell or cmd.exe functionalities. So if you’re not stringing two commands together o variables like $env:HOME and operations like "<", ">", "|", and ";" you don’t really need the win_shell module. Similarly, expanding shell variables requires the win_shell module. If you’re not using these features, don’t use the win_shell module. Sometimes it’s the only way, I know.

demo

Let me show you the difference between win_command vs win_shell Ansible modules in three Ansible Playbooks.

win_command code

---
- name: win_command module demo
  hosts: all
  tasks:
    - name: check netstat
      ansible.windows.win_command: "netstat -e"
      register: command_output
    - name: command output
      ansible.builtin.debug:
        var: command_output.stdout_lines

win_command execution

ansible-pilot $ ansible-playbook -i virtualmachines/win/inventory commmand_shell/win_date.yml
PLAY [win_shell module demo] **********************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [WindowsServer]
TASK [check getdate] ******************************************************************************
changed: [WindowsServer]
TASK [command output] *****************************************************************************
ok: [WindowsServer] => {
    "command_output.stdout_lines": [
        "demo",
        "",
        "Friday, April 8, 2022 11:19:21 AM",
        "",
        ""
    ]
}
PLAY RECAP ****************************************************************************************
WindowsServer              : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $

win_shell code

---
- name: win_shell module demo
  hosts: all
  tasks:
    - name: check getdate
      ansible.windows.win_shell: |
        hostname
        Get-Date        
      register: command_output
    - name: command output
      ansible.builtin.debug:
        var: command_output.stdout_lines

win_shell execution

ansible-pilot $ ansible-playbook -i virtualmachines/win/inventory commmand_shell/win_date.yml
PLAY [win_shell module demo] **********************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [WindowsServer]
TASK [check getdate] ******************************************************************************
changed: [WindowsServer]
TASK [command output] *****************************************************************************
ok: [WindowsServer] => {
    "command_output.stdout_lines": [
        "demo",
        "",
        "Friday, April 8, 2022 18:19:36 AM",
        "",
        ""
    ]
}
PLAY RECAP ****************************************************************************************
WindowsServer              : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $

wrong module code

The win_command doesn’t execute multiple PowerShell lines.

---
- name: win_command module demo
  hosts: all
  tasks:
    - name: check getdate
      ansible.windows.win_command: |
        hostname
        Get-Date        
      register: command_output
    - name: command output
      ansible.builtin.debug:
        var: command_output.stdout_lines

wrong module execution

ansible-pilot $ ansible-playbook -i virtualmachines/win/inventory commmand_shell/win_date_command.yml
PLAY [win_command module demo] ********************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [WindowsServer]
TASK [check getdate] ******************************************************************************
changed: [WindowsServer]
TASK [command output] *****************************************************************************
ok: [WindowsServer] => {
    "command_output.stdout_lines": [
        "demo"
    ]
}
PLAY RECAP ****************************************************************************************
WindowsServer              : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $