Getting Help In The CLI

🛠️ 1. man – Manual Pages

Displays the full manual (documentation) for a command.

man ls

🔹 Scroll with arrow keys or spacebar, exit with q.

You can also search inside the man page using / followed by a keyword.

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🧩 2. --help Option

Most commands support --help to show a quick summary of usage and options.

ls --help

✅ Good for quick reference (less detailed than man).

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📚 3. info – GNU Info System

Gives detailed documentation in a tree structure, often more in-depth than man.

info coreutils 'ls invocation'

Use Tab, Enter, and arrow keys to navigate. Press q to quit.

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🧪 4. whatis – Short Description

Gives a one-line summary of a command.

whatis grep

Output: grep (1) - print lines matching a pattern

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🔍 5. apropos – Search for Commands by Keyword

Searches all man pages for a keyword.

apropos copy

Useful if you don’t know the exact command name.

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🧵 6. type – Find Out What a Command Is

Shows whether a command is built-in, an alias, or an external binary.

type cd

Output: cd is a shell builtin

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🐚 7. help – For Bash Built-in Commands

Use help for built-in Bash commands like cd, echo, if, etc.

help cd

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🔁 8. Tab Completion & compgen

Hit the Tab key once or twice to autocomplete commands or filenames.

You can also list available commands:

compgen -c

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🔧 Bonus: tldr – Simplified Help Pages (if installed)

Provides simplified and community-maintained help pages.

tldr tar

You may need to install it first: sudo apt install tldr or sudo yum install tldr.

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📌 Summary

Tool	Purpose
man	Full manual page
--help	Quick options and usage
info	Structured, detailed documentation
whatis	One-line command description
apropos	Search man pages by keyword
type	Show command type (builtin, etc.)
help	Help for Bash built-ins
tldr	Community-simplified command help
Basic - Command Line Interface