From f5718a354c15acd3a47424318de87b0aeeda1d53 Mon Sep 17 00:00:00 2001
From: Sam Doran <sdoran@redhat.com>
Date: Thu, 4 Jun 2020 17:13:42 -0400
Subject: [PATCH] lineinfile - Add alternative backrefs example to docs
 (#69844)

* lineinfile - Add alternative backrefs example to docs

* Add changelog
---
 .../fragments/lineinfile-backrefs-syntax-example.yaml     | 2 ++
 lib/ansible/modules/lineinfile.py                         | 8 ++++++++
 2 files changed, 10 insertions(+)
 create mode 100644 changelogs/fragments/lineinfile-backrefs-syntax-example.yaml

diff --git a/changelogs/fragments/lineinfile-backrefs-syntax-example.yaml b/changelogs/fragments/lineinfile-backrefs-syntax-example.yaml
new file mode 100644
index 00000000000..9409b24d30c
--- /dev/null
+++ b/changelogs/fragments/lineinfile-backrefs-syntax-example.yaml
@@ -0,0 +1,2 @@
+bugfixes:
+  - lineinfile - add example of using alternative backrefs syntax (https://github.com/ansible/ansible/issues/42794)
diff --git a/lib/ansible/modules/lineinfile.py b/lib/ansible/modules/lineinfile.py
index 2ffa8d74f1b..5860f4d6e73 100644
--- a/lib/ansible/modules/lineinfile.py
+++ b/lib/ansible/modules/lineinfile.py
@@ -200,6 +200,14 @@ EXAMPLES = r'''
     regexp: '^%ADMIN ALL='
     line: '%ADMIN ALL=(ALL) NOPASSWD: ALL'
     validate: /usr/sbin/visudo -cf %s
+
+# See https://docs.python.org/3/library/re.html for further details on syntax
+- name: Use backrefs with alternative group syntax to avoid conflicts with variable values
+  lineinfile:
+    path: /tmp/config
+    regexp: ^(host=).*
+    line: \g<1>{{ hostname }}
+    backrefs: yes
 '''
 
 import os