Commenting out a line with Ansible lineinfile module

问题

I find it hard to believe there isn't anything that covers this use case but my search has proved fruitless.

I have a line in /etc/fstab to mount a drive that's no longer available:

//archive/Pipeline /pipeline/Archives cifs ro,credentials=/home/username/.config/cifs 0   0

What I want is to change it to

#//archive/Pipeline /pipeline/Archives cifs ro,credentials=/home/username/.config/cifs 0   0

I was using this

---
- hosts: slurm
  remote_user: root

  tasks:
    - name: Comment out pipeline archive in fstab
      lineinfile:
        dest: /etc/fstab
        regexp: '^//archive/pipeline'
        line: '#//archive/pipeline'
        state: present
      tags: update-fstab

expecting it to just insert the comment symbol (#), but instead it replaced the whole line and I ended up with

#//archive/Pipeline

is there a way to glob-capture the rest of the line or just insert the single comment char?

 regexp: '^//archive/pipeline *'
 line: '#//archive/pipeline *'

 regexp: '^//archive/pipeline *'
 line: '#//archive/pipeline $1'

I am trying to wrap my head around lineinfile and from what I"ve read it looks like insertafter is what I'm looking for, but "insert after" isn't what I want?

回答1:

You can use the replace module for your case:

---
- hosts: slurm
  remote_user: root

  tasks:
    - name: Comment out pipeline archive in fstab
      replace:
        dest: /etc/fstab
        regexp: '^//archive/pipeline'
        replace: '#//archive/pipeline'
      tags: update-fstab

It will replace all occurrences of the string that matches regexp.

lineinfile on the other hand, works only on one line (even if multiple matching are find in a file). It ensures a particular line is absent or present with a defined content.

回答2:

Use backrefs=yes:

Used with state=present. If set, line can contain backreferences (both positional and named) that will get populated if the regexp matches.

Like this:

- name: Comment out pipeline archive in fstab
  lineinfile:
    dest: /etc/fstab
    regexp: '(?i)^(//archive/pipeline.*)'
    line: '# \1'
    backrefs: yes
    state: present

Also note that I use (?i) option for regexp, because your search expression will never match Pipeline with capital P in the example fstab.

回答3:

This is one of the many reasons lineinfile is an antipattern. In many cases, a template is the best solution. In this case, the mount module was designed for this.

- name: Remove the pipeline archive
  mount: name="/archive/pipeline" state=absent

But "ah!" you say, you "want to preserve that the mount was in fstab at one time". You've done one better by using mount, you've preserved it in ansible.

来源：https://stackoverflow.com/questions/39239602/commenting-out-a-line-with-ansible-lineinfile-module

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