https://stackoverflow.com/questions/77150071/ansible-lineinfile-regexp-line-with-many-spaces

session.txt

$ tree
.
├── su.example
└── test.yml

0 directories, 2 files

$ cat su.example 
#%PAM-1.0
auth            sufficient      pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth           sufficient      pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
#auth           required        pam_wheel.so use_uid
auth            substack        system-auth
auth            include         postlogin
account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet

$ cat test.yml 
---
- hosts: localhost
  gather_facts: false

  tasks:
    - name: Modify PAM
      ansible.builtin.lineinfile:
        path: su.example
        regexp: '^#auth           required        pam_wheel.so use_uid'
        line: 'auth            required        pam_wheel.so use_uid'
        backrefs: true
        backup: true

$ ansible-playbook test.yml 

PLAY [localhost] *******************************************************************************************************************************************************************************************************************

TASK [Modify PAM] ******************************************************************************************************************************************************************************************************************
changed: [localhost]

PLAY RECAP *************************************************************************************************************************************************************************************************************************
localhost                  : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

$ tree
.
├── su.example
├── su.example.441527.2023-09-21@17:06:13~
└── test.yml

0 directories, 3 files

$ diff su.example.441527.2023-09-21@17\:06\:13~ su.example
--- su.example.441527.2023-09-21@17:06:13~      2023-09-21 16:58:16.914213377 +0200
+++ su.example  2023-09-21 17:06:13.074352732 +0200
@@ -3,7 +3,7 @@
 # Uncomment the following line to implicitly trust users in the "wheel" group.
 #auth           sufficient      pam_wheel.so trust use_uid
 # Uncomment the following line to require a user to be in the "wheel" group.
-#auth           required        pam_wheel.so use_uid
+auth            required        pam_wheel.so use_uid
 auth            substack        system-auth
 auth            include         postlogin
 account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet