You'll find that you want to collect "man pages" (manual pages). Create a folder, name it, and start placing man pages there, as you find them. The Mac OS changes, and with it, some of the man pages are different - relative to older man pages. You could look up several online, but you'll learn that your Mac responds to the commands installed (and with those commands installed, are the man pages).
An AppleScript that you can paste into an AppleScript Editor window:
try
set input_text to text returned of (display dialog "Input here:" default answer "")
tell me to do shell script "man " & input_text & " | col -bx > /Users/`logname`/Desktop/" & input_text & ".txt 2>/dev/null ; wait"
end try
Run that, and you'll get the idea. At the prompt, enter the name of a man page that you want to study. Suggested: networksetup (Enter that) and a new text file, networksetup.txt will show on your Desktop.
Get the free text editor, TextWrangler. You'll understand, after using it a while.
Online the Internet, look for the Command Line Administration manual in PDF form, for Apple Mac OS servers. There are different versions, but any would do, as a useful guide.
OSXDaily.com:
http://osxdaily.com/2011/11/02/enable-and-use-the-locate-command-in-the-mac-os-x-terminal/
Useful command line tips:
http://serverfault.com/questions/7346/what-are-useful-command-line-commands-on-mac-os-x
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