Ansible lineinfile duplicates line

Question

I have a simple file at /etc/foo.txt. The file contains the following:

#bar

I have the following ansible playbook task to uncomment the line above:

- name: test lineinfile
  lineinfile: backup=yes state=present dest=/etc/foo.txt
              regexp='^#bar'
              line='bar'

When I first run ansible-playbook, the line gets uncommented and the /etc/foo.txt now contains the following:

bar

However, if I run ansible-playbook again, I get the following:

bar
bar

If I run it yet again, then the /etc/foo.txt file will look like this:

bar
bar
bar

How to avoid this duplications of lines? I just want to uncomment the '#bar' and be done with it.

question from:https://stackoverflow.com/questions/19390600/ansible-lineinfile-duplicates-line

Answer 1

You need to add backrefs=yes if you don't want to change your regular expression.

- name: test lineinfile
  lineinfile: backup=yes state=present dest=/etc/foo.txt
              regexp='^#bar' backrefs=yes
              line='bar'

This changes the behavior of lineinfile from:

 find
 if found
   replace line found
 else
   add line

to:

 find
 if found
   replace line found

In other words, this makes operation idempotent.