Running the following 2 bash commands in Ansible [duplicate] - linux

Question

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Difference between sh and Bash
(11 answers)
shell module: Bash <(process substitution) with ansible
(3 answers)
Closed 6 months ago.
I'm trying to create a playbook that incorporates the following 2 commands and due to their special characters, i cant get it to work. Is there a list of special characters i need to account for in ansible using a bash command?
- name: If file exists compare new users.txt
shell: >
diff -q users.txt <(getent passwd | awk -F: '{ print $1 }') 1>/dev/null; error="$?"
getent passwd | awk -F: '{ print $1 }' > users.txt
The error is
fatal: [localhost]: FAILED! => {
"changed": true,
"cmd": "diff -q users.txt <(getent passwd | awk -F: '{ print $1}') 1>/dev/null; error=\"$?\"\n",
"delta": "0:00:00.002893",
"end": "2022-08-19 23:43:07.324939",
"invocation": {
"module_args": {
"_raw_params": "diff -q users.txt <(getent passwd | awk -F: '{ print $1}') 1>/dev/null; error=\"$?\"\n",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"stdin_add_newline": true,
"strip_empty_ends": true,
"warn": true
}
},
"msg": "non-zero return code",
"rc": 1,
"start": "2022-08-19 23:43:07.322046",
"stderr": "/bin/sh: -c: line 0: syntax error near unexpected token `('\n/bin/sh: -c: line 0: `diff -q users.txt <(getent passwd | awk -F: '{ print $1}') 1>/dev/null; error=\"$?\"'",
"stderr_lines": [
"/bin/sh: -c: line 0: syntax error near unexpected token `('",
"/bin/sh: -c: line 0: `diff -q users.txt <(getent passwd | awk -F: '{ print $1}') 1>/dev/null; error=\"$?\"'"
],
"stdout": "",
"stdout_lines": []
}

Answer 1

Q: "Update the list of users in /tmp/users.txt if the list differs from those in /etc/passwd."
A: Use the module getent to read /etc/passwd. For example,
- name: Create dictionary ansible_facts.getent_passwd
ansible.builtin.getent:
database: passed
Next, read the file. Set changed_when: false to keep the play idempotent
- name: Create list users.stdout_lines from /tmp/users.txt
command: cat /tmp/users.txt
register: users
changed_when: false
Compare the lists and update the file if needed
- copy:
dest: /tmp/users.txt
content: |
{% for user in ansible_facts.getent_passwd.keys() %}
{{ user }}
{% endfor %}
when: diff|length > 0
vars:
diff: ansible_facts.getent_passwd.keys()|list|
difference(users.stdout_lines)
Example of a complete playbook for testing
- hosts: localhost
tasks:
- name: Create dictionary ansible_facts.getent_passwd
ansible.builtin.getent:
database: passwd
- ansible.builtin.debug:
var: ansible_facts.getent_passwd.keys()|list
when: debug|d(false)|bool
- name: Create list users.stdout_lines from /tmp/users.txt
command: cat /tmp/users.txt
register: users
changed_when: false
- ansible.builtin.debug:
var: users.stdout_lines
when: debug|d(false)|bool
- name: Update /tmp/users.txt
copy:
dest: /tmp/users.txt
content: |
{% for user in ansible_facts.getent_passwd.keys() %}
{{ user }}
{% endfor %}
when: new_users|length > 0
vars:
new_users: "{{ ansible_facts.getent_passwd.keys()|
difference(users.stdout_lines) }}"
Example of the update
If I remove the users admin, user1, and user2 from the file, the play gives (abridged) in --diff mode
shell> ansible-playbook pb.yml -CD
TASK [Update /tmp/users.txt] ************************************************
--- before: /tmp/users.txt
+++ after: /home/tester/.ansible/tmp/ansible-local-903563m7yp2ywc/tmpvm5fd7j2
## -50,4 +50,7 ##
libvirt-qemu
libvirt-dnsmasq
asadmin
+admin
+user1
+user2
_chrony
changed: [localhost]
Q: "Detect new users that were added."
A: Report new users in the block. For example,
- hosts: localhost
gather_facts: false
tasks:
- name: Create dictionary ansible_facts.getent_passwd
ansible.builtin.getent:
database: passwd
- ansible.builtin.debug:
var: ansible_facts.getent_passwd.keys()|list
when: debug|d(false)|bool
- name: Create list users.stdout_lines from /tmp/users.txt
command: cat /tmp/users.txt
register: users
changed_when: false
- ansible.builtin.debug:
var: users.stdout_lines
when: debug|d(false)|bool
- name: Report new users and update file
block:
- name: Report new users
debug:
msg: "New users: {{ new_users }}"
- name: Update /tmp/users.txt
copy:
dest: /tmp/users.txt
content: |
{% for user in ansible_facts.getent_passwd.keys() %}
{{ user }}
{% endfor %}
when: new_users|length > 0
vars:
new_users: "{{ ansible_facts.getent_passwd.keys()|
difference(users.stdout_lines) }}"