Chapter 3: Linux Basic Commands
3.9 Getting help
man ls # full manual page (q to quit, /word to search)
ls --help # short usage summary
whatis chmod # one-line description
apropos network # search manual pages by keyword
type cd # is it a built-in, alias or program?
which nginx # full path of a command
Ravindra Bagale's Tip
Before editing any important config file, make a backup: sudo cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.bak. If something breaks, you can restore in one command. This small habit can save your lab server again and again.