playbook

---

- hosts: anna

  tasks:
    - name: Add bob
      sudo: yes
      user: name=bob

    - name: Add some groups
      sudo: yes
      group: name={{ item }}
      with_items:
        - bob
        - cat
        - mouse
        - shovel

    - name: Add bob to groups bob and cat
      sudo: yes
      user: name=bob groups=bob,cat

    - name: Capture what groups bob has
      shell: cat /etc/group | grep bob
      register: bob_output

    - name: See what groups bob has
      debug: var=bob_output

    - name: Add bob to groups mouse and shovel
      sudo: yes
      user: name=bob groups=mouse,shovel append=1

    - name: Capture what groups bob has
      shell: cat /etc/group | grep bob
      register: bob_output

    - name: See what groups bob has
      debug: var=bob_output

results

PLAY [anna] ******************************************************************* 

GATHERING FACTS *************************************************************** 
ok: [anna]

TASK: [Add bob] *************************************************************** 
changed: [anna]

TASK: [Add some groups] ******************************************************* 
ok: [anna] => (item=bob)
changed: [anna] => (item=cat)
changed: [anna] => (item=mouse)
changed: [anna] => (item=shovel)

TASK: [Add bob to groups bob and cat] ***************************************** 
changed: [anna]

TASK: [Capture what groups bob has] ******************************************* 
changed: [anna]

TASK: [See what groups bob has] *********************************************** 
ok: [anna] => {
    "bob_output": {
        "changed": true, 
        "cmd": "cat /etc/group | grep bob ", 
        "delta": "0:00:00.005244", 
        "end": "2014-04-16 21:48:32.018314", 
        "invocation": {
            "module_args": "cat /etc/group | grep bob", 
            "module_name": "shell"
        }, 
        "rc": 0, 
        "start": "2014-04-16 21:48:32.013070", 
        "stderr": "", 
        "stdout": "bob:x:1004:bob\ncat:x:1005:bob", 
        "stdout_lines": [
            "bob:x:1004:bob", 
            "cat:x:1005:bob"
        ]
    }
}

TASK: [Add bob to groups mouse and shovel] ************************************ 
changed: [anna]

TASK: [Capture what groups bob has] ******************************************* 
changed: [anna]

TASK: [See what groups bob has] *********************************************** 
ok: [anna] => {
    "bob_output": {
        "changed": true, 
        "cmd": "cat /etc/group | grep bob ", 
        "delta": "0:00:00.007819", 
        "end": "2014-04-16 21:48:32.675957", 
        "invocation": {
            "module_args": "cat /etc/group | grep bob", 
            "module_name": "shell"
        }, 
        "rc": 0, 
        "start": "2014-04-16 21:48:32.668138", 
        "stderr": "", 
        "stdout": "bob:x:1004:bob\ncat:x:1005:bob\nmouse:x:1006:bob\nshovel:x:1007:bob", 
        "stdout_lines": [
            "bob:x:1004:bob", 
            "cat:x:1005:bob", 
            "mouse:x:1006:bob", 
            "shovel:x:1007:bob"
        ]
    }
}

PLAY RECAP ******************************************************************** 
anna                       : ok=9    changed=6    unreachable=0    failed=0