To get help on commands
help <command name>
eg: help cat
<command name> --help
eg: grep --help
<command name> -h
eg: chmod -h
whatis <command name>
eg: whatis grep
To get man pages
man <command name>
eg: man ls
To search for a particular word within a man page type /word
To quit from a man page, just type the Q key
If you don’t remember the actual command:
man -k <keyword to search>
eg: man -k permission
//You will find a line in the output that looks something like: chmod (1) - change permissions of a file
To get info pages
info <command name>