Whats the difference between ansible 'raw', 'shell' and 'command'?

Question

What is the difference between raw, shell and command in the ansible playbook? And when to use which?

Answer 1

command: executes a remote command on the target host, in the same shell of other playbook's tasks.
It can be used for launch scripts (.sh) or for execute simple commands. For example:

- name: Cat a file
  command: cat somefile.txt

- name: Execute a script
  command: somescript.sh param1 param2

shell: executes a remote command on the target host, opening a new shell (/bin/sh).
It can be used if you want to execute more complex commands, for example, commands concatenated with pipes. For example:

- name: Look for something in a file
  shell: cat somefile.txt | grep something

raw: executes low-level commands where the interpreter is missing on the target host, a common use case is for installing python. This module should not be used in all other cases (where command and shell are suggested)