ansible lineinfile multiple lines

Ansible is a powerful automation tool that can help you manage your infrastructure and configuration files with ease. One of the modules that ansible lineinfile multiple lines, which allows you to ensure a particular line is in a file, or replace an existing line using a regular expression.

However, what if you want to add or modify multiple lines in a file using the lineinfile module? In this article, we will show you how to use the lineinfile module to manage multiple lines in a file, and some tips and tricks to make your Ansible playbook more efficient and readable.

The Basic Syntax of the Lineinfile Module

The basic syntax of the lineinfile module is as follows:

- name: task name
ansible.builtin.lineinfile:
path: /path/to/file
state: present or absent
line: the line to insert or replace
regexp: the regular expression to match
insertafter: the line after which to insert the new line
insertbefore: the line before which to insert the new line
backup: yes or no
create: yes or no

The parameters of the lineinfile module are:

• path: The path of the file to modify. This is a required parameter.
• state: The state of the line in the file. If present, the line will be inserted or replaced if it matches the regexp. If absent, the line will be removed if it matches the regexp. The default value is present.
• line: The line to insert or replace into the file. This is a required parameter when state is present.
• regexp: The regular expression to match the line in the file. If the regexp matches, the line will be replaced by the line parameter. If the regexp does not match, the line will be inserted at the end of the file, or after or before the line specified by the insertafter or insertbefore parameters.
• insertafter: The line after which to insert the new line. This can be a string, a regular expression, or one of the special keywords: BOF (beginning of file), EOF (end of file), None (do not insert, only replace). The default value is EOF.
• insertbefore: The line before which to insert the new line. This can be a string, a regular expression, or one of the special keywords: BOF (beginning of file), EOF (end of file), None (do not insert, only replace). The default value is None.
• backup: Whether to create a backup file of the original file before modifying it. The backup file will have the same name as the original file, with a timestamp appended to it. The default value is no.
• create: Whether to create the file if it does not exist. The default value is no.

How to Use the Lineinfile Module to Manage Multiple Lines in a File

You can use one of these methods, to manage multiple lines in a file,

• Use a loop to iterate over a list of lines and regular expressions
• Use the backrefs parameter to enable backreferences in the line and regexp parameters
• Use the blockinfile module to insert or replace a block of lines in a file

Method 1: Use a Loop to Iterate Over a List of Lines and Regular Expressions

One way to use the lineinfile module to manage multiple lines in a file is to use a loop to iterate over a list of lines and regular expressions. Suppose you want to add or modify the following lines in the /etc/hosts file:

You can use the following Ansible playbook to achieve this:

The loop parameter allows you to iterate over a list of items, each of which is a dictionary that contains the line and regexp parameters for the lineinfile module. The {{ item.line }} and {{ item.regexp }} are variables that refer to the current item in the loop.

This method is useful when you have a small number of lines to add or modify, and you know the regular expressions to match them. It can become tedious and error-prone when you have a large number of lines to manage, or when the regular expressions are complex or dynamic.

Method 2: Use the backrefs Parameter to Enable Backreferences in the line and regexp Parameters

Another way to use the lineinfile module to manage multiple lines in a file is to use the backrefs parameter to enable backreferences in the line and regexp parameters. A backreference is a way to refer to a part of the matched text in the replacement text, using the syntax \n or \g<name>, where n is a number or name is a name that corresponds to a group in the regular expression.

For example, suppose you want to change the port number of a service in the /etc/services file, from 80 to 8080.

Use the following playbook to achieve:

The backrefs parameter is set to yes, which means that the line and regexp parameters can contain backreferences. The regexp parameter matches any line that starts with http, followed by one or more whitespace characters, followed by 80, followed by a slash and any other characters until the end of the line. The parentheses in the regexp parameter create two groups: the first group captures the word http, and the second group captures the slash and the rest of the line. The line parameter uses the backreferences \1 and \2 to refer to the first and second groups, respectively. The replacement line is the same as the original line, except that the port number is changed from 80 to 8080.

When you want to modify a part of a line based on a regular expression, without changing the rest of the line. It requires some knowledge of regular expressions and backreferences, and it can be difficult to read and maintain.

Method 3: Use the blockinfile Module to Insert or Replace a Block of Lines in a File

A third way to use the lineinfile module to manage multiple lines in a file is to use the blockinfile module. The blockinfile module is similar to the lineinfile module, but it allows you to insert or replace a block of lines in a file, delimited by customizable marker lines.

For example, suppose you want to add or modify the following block of lines in the /etc/network/interfaces file:

Use the following Ansible playbook to achieve:

The blockinfile module has the following parameters:

• Path: The path of the file to modify. This is a required parameter.
• State: If present, the block will be inserted or replaced if it matches the marker lines. If absent, the block will be removed if it matches the marker lines. The default value is present.
• Block: Insert or replace into the file. This is a required parameter when state is present. The block should be indented and followed by a newline character.
• Marker: Template that delimits the block. # {mark} ANSIBLE MANAGED BLOCK is a default value, {mark} is a special variable that can be either BEGIN or END. You can customize it by using any other variables or text or expressions. For example, you can use the hostname of the target machine as a variable by using {{ inventory_hostname }}.
• Marker_begin: Template that marks the beginning of the block. This overrides the marker parameter for the beginning of the block.
• Marker_end: Marks at the end of the block. This overrides the marker parameter for the end of the block.
• Insertafter: This can be a string, a regular expression, or one of the special keywords: BOF (beginning of file), EOF (end of file), None (do not insert, only replace). The default value is EOF.
• Insertbefore: This can be a string, a regular expression, or one of the special keywords: BOF (beginning of file), EOF (end of file), None (do not insert, only replace). The default value is None.
• Backup: To create a backup file of the original file before modifying it. The backup file will have the same name as the original file, with a timestamp appended to it. The default value is no.
• Create: Whether to create the file if it does not exist. The default value is no.

Modify file blocks without complex regex or backreferences.

Conclusion

In this article, Where We dicussed “ansible lineinfile multiple lines”., We have shown you how to use the lineinfile module to manage multiple lines in a file, and some tips and tricks to make your Ansible playbook more efficient and readable. We have also introduced the blockinfile module, which is a handy alternative to the lineinfile module for managing blocks of lines in a file. We hope you have learned something useful from this article, and that you will use the Ansible lineinfile multiple lines module and the blockinfile module to automate your configuration file management tasks.