man + cmd usually gives the most in-depth answer when seeking information about a command. Most Linux commands have man pages. Some don’t.
In case of missing man pages, the given command may provide information about itself by one of the following:
cmd --help
cmd -help
cmd -h
Substitute cmd for the command you want to know about.
Additionally, there are special commands on Linux whose function is to provide information about other commands. Some of them are:
type cmd
whatis cmd
whereis cmd
