Using the system reference manuals.

#show the manual of command man
man man

For learning purposes, reading the SYNOPSIS, DESCRIPTION, EXAMPLES, and NOTES sections, skimming the avaible groups of options, don't read linearly. For man pay attentions to:

# Searches names
man -f [whatis options] page ... 
# Searches both names and descriptions for the keyword as a substring/regex. 
man -k [apropos options] regexp ...
# Searchs for text in all manual pages
man -K [man options] [section] term ...

When you encounter something you don't know or unfamiliar with, using these commands to find its manuals for helps.

On that note, execute man less to see how to use it. The most import command of less is h , giving you the help. You might use dayily

• j/k scroll up/down
• Space/b page forward/back
• /pattern search
• n/N next/previous match
• g/G jump to top/bottom
• q quit When you are reading a manual, you can use /^EXAMPLES to jump between sections. --help can give you a help list of any command, like dnf --help.