ansible正则表达式替换所有匹配的string1，排除string2

Question

I'd like to replace all instances of dogs with cats , except for those where the line has does not play with mice .

My file contents looks like:

dogs:plays with mice
dogs:plays with mice
dogs:does not play with mice
dogs:plays with mice
dogs:plays with mice
dogs:does not play with mice
dogs:plays with mice

Below are the important bits to my ansible-playbook, to try achieve the desired result:

  vars:
    file_to_update: /tmp/cats_dogs_file.txt
    exclude: "does not play with mice"
    from_name: "dogs"
    to_name: "cats"

  tasks:    

  - name: updates dogs to cats - excluding the necessary
    replace:
      path: "{{ file_to_update }}"
      regexp: "^{{ from_name }}(?! {{ exclude }})"
      replace: "{{ to_name }}"
    register: file_update_status

I expect the contents of the file to be changed as per the below:

cats:plays with mice
cats:plays with mice
dogs:does not play with mice
cats:plays with mice
cats:plays with mice
dogs:does not play with mice
cats:plays with mice

Instead I currently get all dogs changed to cats .

The exclude is not being adhered to.

Answer 1

Maybe, here we could write an expression and find the parts of your desired output and replace them. Maybe something similar to:

(.+):(plays? with)\s(.+)

JavaScript Demo

 const regex = /(.+):(plays? with)\\s(.+)/gm; const str = `dogs:plays with mice dogs:plays with mice dogs:does not play with mice dogs:plays with mice dogs:plays with mice dogs:does not play with mice dogs:plays with mice cats:plays with mice cats:plays with mice dogs:does not play with mice cats:plays with mice cats:plays with mice dogs:does not play with mice cats:plays with mice`; const subst = `cats:$2 $3`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result); 

Python Test

# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility

import re

regex = r"(.+):(plays? with)\s(.+)"

test_str = ("dogs:plays with mice\n"
    "dogs:plays with mice\n"
    "dogs:does not play with mice\n"
    "dogs:plays with mice\n"
    "dogs:plays with mice\n"
    "dogs:does not play with mice\n"
    "dogs:plays with mice\n\n"
    "cats:plays with mice\n"
    "cats:plays with mice\n"
    "dogs:does not play with mice\n"
    "cats:plays with mice\n"
    "cats:plays with mice\n"
    "dogs:does not play with mice\n"
    "cats:plays with mice")

subst = "cats:\\2 \\3"

# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)

if result:
    print (result)

# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

RegEx

If this wasn't your desired expression, you can modify/change your expressions in regex101.com .

RegEx Circuit

You can also visualize your expressions in jex.im :

Answer 2

A simple solution would be to loop over the lines and conditionally exclude the lines that shall not be replaced.

The play below

tasks:
  - replace:
      path: "{{ file_to_update }}"
      regexp: "{{ item }}"
      replace: "{{ item|regex_replace(from_name, to_name) }}"
    with_lines: "cat {{ file_to_update }}"
    when: exclude not in item

gives (abridged):

TASK [replace] 
******************************************************************************
changed: [localhost] => (item=dogs:plays with mice)
ok: [localhost] => (item=dogs:plays with mice)
skipping: [localhost] => (item=dogs:does not play with mice) 
ok: [localhost] => (item=dogs:plays with mice)
ok: [localhost] => (item=dogs:plays with mice)
skipping: [localhost] => (item=dogs:does not play with mice) 
ok: [localhost] => (item=dogs:plays with mice)

> cat cats_dogs_file.txt
cats:plays with mice
cats:plays with mice
dogs:does not play with mice
cats:plays with mice
cats:plays with mice
dogs:does not play with mice
cats:plays with mice