Replace a line in a config file with ansible

Question

I am new to ansible.

Is there a simple way to replace the line starting with option domain-name-servers in /etc/dhcp/interface-br0.conf with more IPs?

  option domain-name-servers 10.116.184.1,10.116.144.1;

I want to add ,10.116.136.1

Answer 1

You can use the lineinfile Ansible module to achieve that.

  - name: replace line
    lineinfile: 
      path: /etc/dhcp/interface-br0.conf 
      regexp: '^(.*)option domain-name-servers(.*)$' 
      line: 'option domain-name-servers 10.116.184.1,10.116.144.1,10.116.136.1;'
      backrefs: yes

The regexp option tells the module what will be the content to replace.

The line option replaces the previously found content with the new content of your choice.

The backrefs option guarantees that if the regexp does not match, the file will be left unchanged.