1. How to check if a user exists on a node?
emacs /etc/passwd (look for u
2. How to check if a group exists on a node?
emacs /etc/group
3. How to check number of lines in a file?
wc -l file.name
4. How do I securely connect to a node?
ssh kamal@node.com
references: http://www.cyberciti.biz/faq/linux-check-existing-groups-users/