# question on lineinfile module **URL:** \ **Category:** Ansible Project\ **Created:** [June 29, 2016, 6:07am UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884 "2016-06-29T06:07:25Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Werner\_Flamme](https://avatars.discourse-cdn.com/v4/letter/w/c68b51/32.png) [@Werner\_Flamme](https://forum.ansible.com/u/Werner_Flamme)\ **Post date:** [June 29, 2016, 6:07am UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884/1 "2016-06-29T06:07:25Z")
Hi everyone, I have one play that does not do what I want it to: - name: set kernel multiversions   lineinfile:     dest: /etc/zypp/zypp.conf     line: "multiversion.kernels = latest,oldest,running"     regexp: "multiversion.kernels = latest,latest-1,running"     state: present I expect -\> the module scans for a line matching "regex" -\> if this is found, the found line is replaced with "line" -\> if "regex" has no matches, nothing is done The module instead scans the file, and on the first run it behaves as I expect, the line in the file is modified. On subsequent runs, one line (per run) is added to the file (before EOF), so that I have multiple lines containing "line". Is this behaviour expected? How can I make a replacement only when "regex" matches? When using a registered variable, this variable is shown as: ok: [hostname] =\> {     "myrole\_var1": {         "backup": "",         "changed": true,         "diff": [             {                 "after": "",                 "after\_header": "/etc/zypp/zypp.conf (content)",                 "before": "",                 "before\_header": "/etc/zypp/zypp.conf (content)"             },             {                 "after\_header": "/etc/zypp/zypp.conf (file attributes)",                 "before\_header": "/etc/zypp/zypp.conf (file attributes)"             }         ],         "msg": "line added"     } } So nothing I could use "when" on. I use the blockinfile module to add a line in this file, but I do not see how to use this module to replace one line. This module runs only once, on subsequent runs it says "OK" instead of "Changed". Regards, Werner ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [June 29, 2016, 1:21pm UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884/2 "2016-06-29T13:21:48Z")
No, and you are not alone [https://github.com/ansible/ansible-modules-core/issues/3975](https://github.com/ansible/ansible-modules-core/issues/3975) ---
**Author:** ![jdelaporte](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/jdelaporte/32/366_2.png) [@jdelaporte](https://forum.ansible.com/u/jdelaporte)\ **Post date:** [June 29, 2016, 6:59pm UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884/3 "2016-06-29T18:59:16Z")
Hi Werner, You would want to use the backrefs feature of the lineinfile module. Here is an example that I use for deleting root password hashes from the /etc/shadow file. I use regex numbered groups (with parens and \1, etc) to capture and replay existing parts of lines as needed: - name: delete root password lineinfile: ‘dest=/etc/shadow backup=yes backrefs=yes regexp=“^(root):._?:(._)$” line=“\1:\*:\2”’ And another example (two tasks) that update an ntp config with a new IP address: # The following two tasks will replace existing ntp config from .135 to .133 - name: Fix ntp.conf lineinfile: dest=/etc/ntp.conf backup=yes state=present backrefs=yes regexp=‘^(._server._) 192.168.1.135’ line=‘\1 192.168.1.133’ - lineinfile: dest=/etc/ntp.conf state=present backup=yes backrefs=yes regexp=‘^(._restrict._) 192.168.1.135’ line=‘\1 192.168.1.133’ ---
**Author:** ![Werner\_Flamme](https://avatars.discourse-cdn.com/v4/letter/w/c68b51/32.png) [@Werner\_Flamme](https://forum.ansible.com/u/Werner_Flamme)\ **Post date:** [June 30, 2016, 6:20am UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884/4 "2016-06-30T06:20:06Z")
Kai Stian Olstad [29.06.2016 15:21]: > > The module instead scans the file, and on the first run it behaves as I > > expect, the line in the file is modified. On subsequent runs, one line > > (per run) is added to the file (before EOF), so that I have multiple > > lines containing "line". > > > > Is this behaviour expected? How can I make a replacement only when > > "regex" matches? > > No, and you are not alone > [https://github.com/ansible/ansible-modules-core/issues/3975](https://github.com/ansible/ansible-modules-core/issues/3975) Yes, that's exactly what happens here. Thank you for pointing me there. I already thought of using an "absent" and a "present" task, but now I use the replace module, and it seems to work: - name: replace kernel multiversions   replace:     dest: /etc/zypp/zypp.conf     regexp: "^multiversion.kernels = latest,latest-1,running"     replace: "multiversion.kernels = latest,oldest,running" BTW, I'm running ansible version 2.1.0.0, and it's the first time I use the lineinfile module (since I'm quite new to ansible). Regards, Werner ---
**Author:** ![Werner\_Flamme](https://avatars.discourse-cdn.com/v4/letter/w/c68b51/32.png) [@Werner\_Flamme](https://forum.ansible.com/u/Werner_Flamme)\ **Post date:** [June 30, 2016, 6:43am UTC](https://forum.ansible.com/t/question-on-lineinfile-module/21884/5 "2016-06-30T06:43:17Z")
Hi Joanna, so using lineinfile with regexp, but without backrefs will duplicate a line and lineinfile with regexp and backrefs will not? Indeed, it seems to be like that. - name: another replacement attempt   lineinfile:     dest: /etc/zypp/zypp.conf     backrefs: yes     regexp: '^(multiversion.kernels = latest),(latest-1),(running)$'     line: '\1,oldest,\3'     state: present works as expected and does not create a duplicate line if regexp is not found. The registered variable shows '"changed": false'. I added that to the bug report... This behaviour is not documented on \<[http://docs.ansible.com/ansible/lineinfile\_module.html>](http://docs.ansible.com/ansible/lineinfile_module.html>), so I consider this as an error. Werner Joanna Delaporte [29.06.2016 20:59]: