Ansible Ad-Hoc Commands

Ansible Ad-Hoc commands are one-off commands that allow users to perform a specific task on a number of managed nodes without needing to write a playbook. They are useful for quick tasks such as installing packages, copying files, or restarting services.

• Inventory: A file specifying the hosts on which commands will be executed.
• Module: A tool to perform a specific task (e.g., yum, copy, service).
• Ad-Hoc Commands: Simple commands executed directly on the command line.

Ad-Hoc commands can be executed using the following syntax:

ansible <host-pattern> -m <module-name> -a "<module-arguments>"

Where:

• <host-pattern>: Specifies the group of hosts or individual hosts.
• <module-name>: The Ansible module you want to use.
• <module-arguments>: The arguments specific to the module.

Example 1: Ping All Hosts

ansible all -m ping

This command checks if all hosts in the inventory can be reached.

Example 2: Install a Package

ansible webservers -m yum -a "name=httpd state=present"

This installs the httpd package on all hosts in the webservers group.

Example 3: Restart a Service

ansible dbservers -m service -a "name=mysqld state=restarted"

This command restarts the mysqld service on all hosts in the dbservers group.

• Always use the correct host pattern to avoid unintended executions.
• Test commands on a single host before applying them to multiple hosts.
• Keep your inventory up to date for effective management.