i can find example of any module…how can i find use of other keywords like when, failed_when, error handling etc…documentation using ansible-doc?
I don’t know if i understand your question but keywords like when, failed_when … is part of playground language you can use the online documentation for that :
https://docs.ansible.com/ansible/latest/playbook_guide/playbooks.html
ansible-doc is used to display information about module
https://docs.ansible.com/ansible/latest/cli/ansible-doc.html