Getting older, not necessarily wiser!
One of the great things about the Linux command line interface is the built in documentation. Man Pages (Manual pages) are a primary example of this. Information about almost every command line function at your fingertips using the man command.
The syntax of the man command in Linux is:
man [options] <command-name> [section]
The man command displays a summary of the command-name. The section variable can be used to refer to specific sections of the Man Pages.
There is some difference between the Linux and Unix specifics for the section command. The above should work for most Linux systems.
The man page generally follows this format.
When a man page is displayed, the arrow keys are used to navigate, and the q key is used to exit back to the command line.
If you want to find out about the man command and all its options, entering man man will bring up the section one man shell command page. Note that there is also a miscellaneous man page for man. If you type man man.7 you will go to the section 7 man page.
Likewise, there is a section 1 man page for printf (the command line printf). There is a section 3 man page for the programming library call for printf, man printf and man printf.3 respectively.
Entering man ext4 will take you to the section 5 man page for the ext file system format for ext2, ext3, and ext4. Note there is no section 1 page for the ext file system, a sit is not a shell command.
The man command is straight forward and easy to use. It gives you information specific to your system, as sometimes man pages looked up on line may be for a different distribution and not be 100% compatible with what you are running.
So whenever you have a question about something you are doing form the command line, answers are just a few short keystrokes away.