Ansible will try to find a configuration file from:

• ANSIBLE_CONFIG environment variable
• ansible.cfg (in the current directory)
• .ansible.cfg (in the home directory)
• /etc/ansible/ansible.cfg

Example ansible.cfg with a comment:

[defaults]
inventory = ./inventory.py  ; This points to the file that lists your hosts
host_key_checking = False

And now you don't have to specify the inventory file -i.

ansible all -m ping

More details in Ansible config documentation.

Sources

• Getting started with ansible in 5 minutes