How to Search for a String in a File with Ansible?

I'm going to show you some simple Ansible code.

I'm Luca Berton and welcome to today's episode of Ansible Pilot.

Ansible module lineinfile

> ansible.builtin.lineinfile: insert, update and remove a single line of text in a file

Today we're talking about the Ansible module lineinfile.

The full name is ansible.builtin.lineinfile, which means that is part of the collection of modules "builtin" with ansible and shipped with it.

It's a module pretty stable and out for years and it supports a large variety of operating systems.

You are able to insert, update and remove a single line of text in a file.

Parameters

  • path string - file path
  • line string - text
  • insertafter/insertbefore string - EOF/regular expression
  • validate string - validation command
  • create boolean - create if not exist
  • state string - present/absent
  • mode/owner/group - permission
  • setype/seuser/selevel - SELinux

This module has some parameters to perform any tasks.

The only required is "path", where you specify the filesystem path of the file you're going to edit.

"line" is the line of text we would like to insert in the file, easy!

By default, the text is going to be inserted at the end of the file, but we could personalize it in a specific position with insertafter/insertbefore.

If there is any tool to validate the file we could specify in the validate parameter, very useful for configuration files.

If the file does not exist we could also "create" it!

Usually, we would like to insert a text line but we could also remove using state in conjunction with parameter absent.

Let me also highlight that we could also specify some permissions or SELinux properties.

Links

  • [ansible.builtin.lineinfile](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/lineinfile_module.html)

Playbook

How to Search for a String in a File.

How to search for a pattern in a file and return the result using only the Ansible built-in lineinfile module.

code

``yaml

---

  • name: search Playbook

hosts: all

vars:

myfile: "/etc/ssh/sshd_config"

myline: 'PasswordAuthentication no'

become: true

tasks:

- name: string found

ansible.builtin.lineinfile:

name: "{{ myfile }}"

line: "{{ myline }}"

state: present

check_mode: true

register: conf

failed_when: (conf is changed) or (conf is failed)

`

string present

  • remote host

`bash

$ ssh [email protected]

[devops@demo ~]$ sudo su

[root@demo devops]# grep 'PasswordAuthentication no' /etc/ssh/sshd_config

PasswordAuthentication no

[root@demo devops]#

`

  • Ansible execution

``bash

$ ansible-playbook -i virtualmachines/demo/inventory file_management/file_search.yml

PLAY [search Playbook]

TASK [Gathering Facts]