# replace module regexp with newline character **URL:** \ **Category:** Ansible Project\ **Created:** [March 21, 2019, 5:02pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940 "2019-03-21T17:02:36Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 21, 2019, 5:02pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/1 "2019-03-21T17:02:36Z")
I need to use replace to find a regexp that includes \n; however, I keep getting an error. How can I properly do this (don’t even know if I am using back reference correct either, but if I can get past this error I think I can figure that part out)? Thanks in advance! ` ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 21, 2019, 5:04pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/2 "2019-03-21T17:04:48Z")
Sorry, last error message is slightly innaccurate… I was testing a change in that one (difference is brackets ): ` TASK [dns\_update : include\_tasks] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* fatal: [ansible-ub18]: FAILED! =\> {“reason”: “Syntax Error while loading YAML.\n found unknown escape character\n\nThe error appears to have been in ‘/etc/ansible/role/dns\_update/tasks/Ubuntu18.yml’: line 7, column 15, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n regexp: "._nameservers._$\n._addresses:(._$)"\n replace: "\1 {{ dns1 }}, {{ dns 2}}"\n ^ here\nWe could be wrong, but this one looks like it might be an issue with\nmissing quotes. Always quote template expression brackets when they\nstart a value. For instance:\n\n with\_items:\n - {{ foo }}\n\nShould be written as:\n\n with\_items:\n - "{{ foo }}"\n”} ` ---
**Author:** ![sivel](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/sivel/32/1198_2.png) [@sivel](https://forum.ansible.com/u/sivel)\ **Post date:** [March 21, 2019, 5:06pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/3 "2019-03-21T17:06:58Z")
I’d recommend any time you need to use escape characters, that you use single quotes around the value, instead of double quotes. It will resolve many of the issues with how pyyaml does it’s parsing ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 21, 2019, 5:10pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/4 "2019-03-21T17:10:13Z")
I have tried single quotes too around the regexp, but get a similar issue ` TASK [dns\_update : include\_tasks] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* fatal: [ansible-ub18]: FAILED! =\> {“reason”: “Syntax Error while loading YAML.\n found unknown escape character\n\nThe error appears to have been in ‘/etc/ansible/role/dns\_update/tasks/Ubuntu18.yml’: line 7, column 15, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n regexp: ‘._nameservers._$\n._addresses:(._$)’\n replace: "\1 {{ dns1 }}, {{ dns 2}}"\n ^ here\nWe could be wrong, but this one looks like it might be an issue with\nmissing quotes. Always quote template expression brackets when they\nstart a value. For instance:\n\n with\_items:\n - {{ foo }}\n\nShould be written as:\n\n with\_items:\n - "{{ foo }}"\n”} ` ---
**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:** [March 21, 2019, 6:10pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/5 "2019-03-21T18:10:48Z")
If you add this sed to correct the formatting somewhat   ansible-playbook playbbok.yml | sed 's/\\n/\n/g' you'll see that is pointing to your double quote in the replace line. ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 21, 2019, 7:51pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/6 "2019-03-21T19:51:28Z")
Thx all. Those helped. I now get it to replace, but it replaces my string and not just my backref. Not sure what I am doing wrong. I think that is just the default behavior of replace. Can’t use quantifiers with negative look aheads/behinds. ---
**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:** [March 21, 2019, 8:46pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/7 "2019-03-21T20:46:38Z")
It will be easier to help if you could show what do have in the file and what is should be after replace. ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 22, 2019, 3:11pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/8 "2019-03-22T15:11:03Z")
I didn’t post it so as to not overburden everyone with my issues; however, if it isn’t a big issue I could use some help as I can’t seem to get it working. I am trying to replace the DNS servers, located in the second addresses line toward the bottom. ` network: ethernets: enp0s3: addresses: [10.10.50.0/24] gateway4: 10.10.50.5 dhcp4: no nameservers: addresses: [10.1.2.3, 10.1.2.4] version: 2 ` ---
**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:** [March 22, 2019, 4:41pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/9 "2019-03-22T16:41:24Z")
> > It will be easier to help if you could show what do have in the file and > > what is should be after replace. > > > > -- > > Kai Stian Olstad > > I didn't post it so as to not overburden everyone with my issues; however, Regexp is not easy without having the actual text it's going to parse, especially when you don't know if your regexp is working. > if it isn't a big issue I could use some help Never is with all the relevant information. > as I can't seem to get it > working. I am trying to replace the DNS servers, located in the second > addresses line toward the bottom. > > network: >      ethernets: >          enp0s3: >              addresses: [10.10.50.0/24] >              gateway4: 10.10.50.5 >              dhcp4: no >              nameservers: >                      addresses: [10.1.2.3, 10.1.2.4] >      version: 2 This made it a lot easier and only took a minute to solve(hopefully since it's not tested). Try this :   regexp: '(.\*nameservers.\*$\n.\*addresses:).\*$'   replace: '\1 [{{ dns1 }}, {{ dns2 }}]' ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 22, 2019, 4:47pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/10 "2019-03-22T16:47:32Z")
Thx Kai. I tried it, and the regexp test shows that the regexp is good, but it doesn’t replace the line. It just says ok, and continues on. Here is my slightly modified variant also doing the same thing (or to be more specific, not doing anything): ` regexp: ‘nameservers:\n._addresses:._[(.\*)]’ line: ‘\1 {{ dns1 }}, {{ dns2 }}’ ` Result: ` TASK [dns\_update : Update DNS servers] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ok: [ansible-ub18] ` File remains the same ---
**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:** [March 22, 2019, 5:01pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/11 "2019-03-22T17:01:15Z")
> Thx Kai. > > I tried it, and the regexp test shows that the regexp is good, but it > doesn't replace the line. It just says ok, and continues on. Here is my > slightly modified variant also doing the same thing (or to be more > specific, not doing anything): > >      regexp: 'nameservers:\n.\*addresses:.\*\[(.\*)\]' >      line: '\1 {{ dns1 }}, {{ dns2 }}' Replace doesn't have line: to my knowledge. > Result: > > TASK [dns\_update : Update DNS servers] > \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* > ok: [ansible-ub18] > > File remains the same So, to check I created a little test with my regexp to see if it work, and it does. $ more dns.yaml network:     ethernets:         enp0s3:             addresses: [10.10.50.0/24]             gateway4: 10.10.50.5             dhcp4: no             nameservers:                     addresses: [10.1.2.3, 10.1.2.4]     version: 2 $ cat test.yml ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 22, 2019, 5:23pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/12 "2019-03-22T17:23:15Z")
You are right… I switched to lineinfile sometime between yesterday and today. I switched back to replace due to your success (and I prefer to use it as I believe it will replace all found instances). Seems to be working now, however, one follow-up question regarding backrefs. I thought \1 replaced the content of group1? Is that incorrect? The content that was replaced doesn’t fall in a group (sorry, I lack experience with backrefs). Here is my regex tester. You can see the “full match” is replaced, and not the “Group 1”: [https://regex101.com/r/jfGg83/4](https://regex101.com/r/jfGg83/4) ---
**Author:** ![John\_Harmon](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@John\_Harmon](https://forum.ansible.com/u/John_Harmon)\ **Post date:** [March 22, 2019, 6:49pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/13 "2019-03-22T18:49:51Z")
Oh, I think I misunderstood (as I suspected) how backrefs work with substitution. I thought what was referenced was being replaced, when in reality it seems to just be putting back what we want to keep and just replacing the rest. ---
**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:** [March 24, 2019, 8:35pm UTC](https://forum.ansible.com/t/replace-module-regexp-with-newline-character/29940/14 "2019-03-24T20:35:06Z")
Yes, all the things matching the regexp: line will be replaced with the content of the replace: line. Since nameservers: and address: shouldn't be discard/replace, the parenthesis around them make it so that we can reference them as \1 in the replace: line.