Locate, read, and use system documentation (man, info, /usr/share/doc)

1. Understand and Use Essential Tools

📘Red Hat Certified System Administrator (RHCSA – EX200)


Linux systems provide built-in documentation to help you understand commands, configuration files, and system functions. As a system administrator, knowing how to find and read documentation is essential, because you can’t memorize every command or option.

The main sources of documentation in Linux are:

  1. man pages
  2. info pages
  3. Documentation files in /usr/share/doc
  4. Other online or installed docs (less common in EX200)

We will focus on the first three because they are exam-relevant.


1. man pages – The manual pages

  • Purpose: man (short for manual) shows detailed information about commands and system functions.
  • Usage: man <command>
  • Example:
man ls

This shows information about the ls command, including:

  • NAME: The command name and short description
  • SYNOPSIS: How to use it (options and arguments)
  • DESCRIPTION: What it does
  • OPTIONS: List of command options with explanations
  • EXAMPLES: Sometimes included
  • SEE ALSO: Related commands

Useful man options

OptionDescription
man -k keywordSearch for commands related to a keyword (like a mini index). Example: man -k network
man -f commandShows a short description of a command (same as whatis). Example: man -f passwd
man -a commandShows all man pages for a command if multiple exist (e.g., man -a printf)
/patternSearch for a word in the man page. Example: /option
nGo to next search match in man page

Exam Tip: Always know how to use man to check command options. You don’t need to memorize every option; you need to know how to find it fast.


2. info pages – The info documentation

  • Purpose: info pages are like a more detailed and structured manual than man. Some commands have extra explanations and links inside.
  • Usage: info <command>
  • Example:
info ls
  • Navigation inside info pages:
    • Arrow keys → scroll up/down
    • Enter → follow a link
    • q → quit
    • Space → scroll forward one screen
  • Differences from man:
    • info often contains more examples
    • man is simpler and more common for exam questions
    • Use info when man is not enough

3. Documentation in /usr/share/doc

  • Purpose: Many packages provide text files with additional documentation inside /usr/share/doc.
  • Typical files you find:
    • README
    • INSTALL
    • LICENSE
    • Examples
  • Path usage:
ls /usr/share/doc

This shows directories for installed software. For example:

ls /usr/share/doc/httpd

You might see:

README
CHANGES
COPYING
  • How to read: Use commands like cat, less, or more:
less /usr/share/doc/httpd/README
  • Why it’s useful: Sometimes commands have options not fully explained in man or info. The docs may have real-world examples, configurations, or limitations.

4. Quick ways to locate documentation

Sometimes you want all sources of info for a command or package:

  • man -k keyword → find commands related to a topic
  • whatis command → quick one-line description
  • rpm -qf /usr/bin/command → find the package that provides a command
  • Then check /usr/share/doc/<package> for detailed documentation

5. Best practices for the exam

  1. Know man inside out:
    • man command → basic usage
    • man -k keyword → search for commands
    • /searchterm → find a specific option inside a man page
  2. Check /usr/share/doc for configuration files
    • Especially after installing packages, check README or examples
  3. Use info when you need extra detail
    • Example: info coreutils
  4. Don’t memorize everything
    • Focus on how to locate and use documentation quickly

6. Sample Exam Tasks

You may be asked:

  • Task: Find the option in tar to compress using gzip.
    Solution: man tar /gzip
  • Task: Check the README for httpd configuration tips.
    Solution: less /usr/share/doc/httpd/README
  • Task: Search for all commands related to users.
    Solution: man -k user

Summary

  • man → the most common, command-focused manual
  • info → more detailed and structured information
  • /usr/share/doc → package-specific docs, examples, and configs
  • Always know how to search and navigate, not memorize everything
  • Essential skill for RHCSA: find info quickly during the exam
Buy Me a Coffee