How To Find Command Help In Linux (Man, Info, Apropos, Whatis, –help)

When I first started using Linux, I often felt lost because I couldn't remember all the commands or their options. The good news is that Linux already gives us powerful tools to solve this problem.

In this guide, I'll show you how I use the popular Linux help commands such as apropos, whatis, info, man, and --help to find help for commands in Linux. I'll also share a few extra command line tips that make the process even easier.

Finding Command Help in Linux

Linux has hundreds of commands. Even seasoned users can't remember every flag or sub-option. Instead of searching online each time, you can rely on built-in tools that deliver quick and accurate information.

Knowing how to use these tools will save you time, help you troubleshoot faster, and make you more confident at the terminal.

1. Use apropos to Search for Related Commands

Sometimes I don't know the exact command name, but I know the task. That's when I run apropos. It searches through manual page descriptions and lists all commands related to a keyword.

Example:

apropos network

This will list commands related to networking, like ping, ifconfig, or ip.

Here's another example:

apropos time

Now I'll see every command with "time" in its description. It's like having a built-in search engine inside the terminal.

Read more about Apropos here: How To Easily Recall Forgotten Linux Commands Using Apropos

2. Use whatis for Quick Descriptions

When I already know the command name but just need a reminder, I use whatis. It gives me a one-line description of the command.

Example:

whatis ls

Sample Output:

ls (1)               - list directory contents

This is perfect for quick lookups when I don’t want to open a full manual.

3. Use info for Detailed GNU Documentation

Some commands include info pages, which are often more detailed than man pages. They are structured like a hyperlinked document, so I can jump between sections.

Example:

info ls

This shows the complete GNU manual for ls. I can navigate sections, search for keywords, and press q to quit when I’m done.

Another useful trick:

info coreutils 'ls invocation'

This jumps straight into the section about how to invoke ls.

4. Use man to Read the Manual Pages

The man command is the classic way to read documentation in Linux. It gives official manuals, syntax details, and option explanations.

Example:

man tar

Inside the manual, I use the arrow keys to scroll, /keyword to search, and q to exit.

Pro tip: man pages are divided into sections. For example, man 5 passwd shows documentation for the passwd file format, while man 1 passwd shows the user command.

You might also want to check our detailed guide on how to use man pages effectively.

5. Use --help for a Quick Usage Summary

Most commands support the --help option, which prints a short summary. I use this when I want to quickly check command-line options.

Example:

grep --help

This shows syntax, available options, and a short description of each. Its ideal when I don't need a deep explanation.

Other Helpful Tools for Finding Command Usage

Alongside the main five, there are a few extra commands that I often use to find a Linux command help.

1. Search for Brief Description and manual Pages with man -k <keyword>

This is the same as apropos.

Example:

man -k copy

2. Print Short Descriptions using man -f <command>

This works like whatis.

Example:

man -f grep

Sample Output:

grep (1)             - print lines that match patterns

3. help (for shell built-ins)

For built-in commands like cd, echo, or alias:

help cd

4. Find Command Type with type

Shows if something is a binary, shell built-in, or alias:

type cd
type ls

Recommended Read: The Type Command Tutorial With Examples For Beginners

5. tldr (Community-maintained Simplified Pages)

Provides practical examples of how to use a command.

Example:

tldr tar

You can install it with:

sudo apt install tldr     # Debian/Ubuntu
sudo dnf install tldr     # Fedora
npm install -g tldr       # via Node.js

Related Read: Search, Study And Practice Linux Commands On The Fly Using Tldr++

6. Read Info Documents with info --apropos <keyword>

Searches the Info system instead of man pages:

info --apropos copy

You may need to install the info command on your system:

sudo apt install info

Compatibility Notes

• man and --help are always available on almost every Linux system.
• apropos and whatis need the man-db package.
• info comes from the texinfo package.
• On minimal distros like Alpine Linux, only --help may be available by default.

How I Combine These Tools

Here's my simple workflow:

1. If I don't know which command to use, I will use apropos.
2. If I know the command but want a short line, I use whatis.
3. If I want detailed GNU docs, I prefer info.
4. If I want the standard manual, I choose man.
5. If I want a quick summary, I use --help flag with the command.
6. If it's a shell built-in, I use help.
7. If I want quick, practical examples, I use tldr.

FAQs About Finding Linux Command Help

TL;DR: Quick Linux Command Help Cheatsheet

• man <command>: Full manual page (detailed documentation).
• <command> --help: Quick usage and options overview.
• whatis <command>: One-line description of a command.
• apropos <keyword>: Search commands by keyword in man pages.
• info <command>: GNU-style detailed documentation.
• help <command>: Help for shell built-ins (like cd, echo).
• type <command>: Check if it’s a built-in, alias, or binary.
• whereis <command>: Show locations of binary, source, and man page.
• which <command>: Show which binary will run.
• tldr <command>: Community-driven simplified examples.

Conclusion

Learning Linux commands isn't about memorizing every detail. Instead, it's about knowing how to find the right information at the right time. With apropos, whatis, info, man, --help, and the other tools I mentioned, you have everything you need built right into the terminal.

Next time you're stuck, try these commands first. You might find the answer faster than opening your browser.

Related Read:

• Fundamental Linux Commands For Newbies
• 15 Essential Linux Commands Every Beginner Should Know
• Linux Command Line Tricks For Efficient And Faster Workflow