An Ansible ad-hoc command uses the /usr/bin/ansible command-line tool to automate a single task on one or more managed nodes. Ad-hoc commands are quick and easy, but they are not reusable. So why learn about ad-hoc commands first? Ad-hoc commands demonstrate the simplicity and power of Ansible. The concepts you learn here will port over directly to the playbook language.
Why use ad-hoc commands?
Ad-hoc commands are great for tasks you repeat rarely. For example, if you want to power off all the machines in your lab for Christmas vacation, you could execute a quick one-liner in Ansible without writing a playbook.
Use cases for ad-hoc tasks
Ad-hoc tasks can be used to reboot servers, copy files, manage packages and users, and much more. You can use any Ansible module in an ad-hoc task. Ad-hoc tasks, like playbooks, use a declarative model, calculating and executing the actions required to reach a specified final state. They achieve a form of idempotence by checking the current state before they begin and doing nothing unless the current state is different from the specified final state.
Example: [student@ansible ~]$ ansible all -m command -a ‘uname -r’ -o
TASK BY TRAINER:
Run an Ansible ad hoc command to install the package “nfs-utils” in the latest version on node1.