How to do multiline shell script in Ansible

Question

right now I am using a shell script in ansible that would be much more readable if it was on multiple lines

- name: iterate user groups
  shell: groupmod -o -g {{ item['guid'] }} {{ item['username'] }} ....more stuff to do
  with_items: "{{ users }}"

Just not sure how to allow multiline script in Ansible shell module

Answer 1

Ansible uses YAML syntax in its playbooks. YAML has a number of block operators:

• The > is a folding block operator. That is, it joins multiple lines together by spaces. The following syntax:

  key: >
    This text
    has multiple
    lines
  

  Would assign the value This text has multiple lines\n to key.

• The | character is a literal block operator. This is probably what you want for multi-line shell scripts. The following syntax:

  key: |
    This text
    has multiple
    lines
  

  Would assign the value This text\nhas multiple\nlines\n to key.

You can use this for multiline shell scripts like this:

- name: iterate user groups
  shell: |
    groupmod -o -g {{ item['guid'] }} {{ item['username'] }} 
    do_some_stuff_here
    and_some_other_stuff
  with_items: "{{ users }}"

There is one caveat: Ansible does some janky manipulation of arguments to the shell command, so while the above will generally work as expected, the following won't:

- shell: |
    cat <<EOF
    This is a test.
    EOF

Ansible will actually render that text with leading spaces, which means the shell will never find the string EOF at the beginning of a line. You can avoid Ansible's unhelpful heuristics by using the cmd parameter like this:

- shell:
    cmd: |
      cat <<EOF
      This is a test.
      EOF

Answer 2

Tried with ansible 2.0.0.2:

---
- hosts: all
  tasks:
    - name: multiline shell command
      shell: >
        ls --color
        /home
      register: stdout

    - name: debug output
      debug: msg={{ stdout }}

The shell command is collapsed into a single line, as in ls --color /home

Reference (visited in 2021): https://docs.ansible.com/ansible/latest/reference_appendices/YAMLSyntax.html ==> search form "multiple lines" in the page.

Answer 3

Adding a space before the EOF delimiter allows to avoid cmd:

- shell: |
    cat <<' EOF'
    This is a test.
    EOF

Answer 4

I prefer this syntax as it allows to set configuration parameters for the shell:

---
- name: an example
  shell:
    cmd: |
      docker build -t current_dir .
      echo "Hello World"
      date

    chdir: /home/vagrant/

Answer 5

A quick caveat about the folding > operator that had me scratching my head for a while: the rows indented beneath it have to be at the same indentation level for the folding to happen correctly, at least when using Ansible.

I was converting an existing multi-line shell command that had \ line endings to escape newlines and had indented every row below the first one two spaces more. I used shell: >, removed the backslashes and preserved the existing indentation.

The newlines were preserved, and I was losing my mind, because everywhere it said that > should convert them to spaces.

See below for an example:

# Converts into ls -la /tmp, as expected
- name: working shell command that folds newlines
  shell: >
    ls
    -la
    /tmp

# Tries to run -la and /tmp as their own commands
- name: failing shell command that does not fold newlines
  shell: >
    ls
      -la
      /tmp

Hope this helps someone in a similar situation!

Answer 6

You can use lineinfile collection to append the file, attribute create to create file if not exist and multi line string using "|".

- name: Add a line to a file if the file does not exist
  ansible.builtin.lineinfile:
    path: ~/.ssh/config
    line: |
      Host {{item.COMPONENT}} {{item.COMPONENT}}.{{ZONE}}
        HostName {{r53_var_one.resource_record_sets[0].resource_records[0].value}}
        User centos
        Port 22
        IdentityFile ~/.ssh/key.pem
        StrictHostKeyChecking no
    create: yes
    mode: '0600'

Answer 7

To know how to multilines works in ansbile, you may want to test this playbook to actually know what pipe (LF->LF) and Greather than (LF->space) are about.

- hosts: all,localhost
  tasks:
   - name: greather_than
     debug:
      msg: >
        a
        b
        c
   - name: pipe
     debug:
      msg: |
        a
        b
        c

This is tested this way.

# ansible-playbook test.yml
 [WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'


PLAY [all,localhost] ***************************************************************************

TASK [Gathering Facts] *************************************************************************
ok: [localhost]

TASK [greater_than] ****************************************************************************  
ok: [localhost] => {
    "msg": "a  b c\n"
}

TASK [pipe] ***********************************************************************************
ok: [localhost] => {
    "msg": "a \nb\nc\n"
}

 PLAY RECAP  ***********************************************************************************
 localhost                  : ok=3    changed=0    unreachable=0    failed=0       skipped=0    rescued=0    ignored=0

#