How to Read Manual Pages in Linux Using the man Command

Introduction

The man (manual) command is an important tool that provides detailed information about Linux commands and programs. It provides comprehensive documentation, including descriptions, options, usage examples, and related information about commands or a specific program.

This article explains how to use the man command in Linux to access and read manual pages.

man Command Syntax

Below is the basic man command syntax:

$ man [option] command_name

Within the above command, command_name sets the name of the command or program to view its manual page.

man Command Syntax

Practical Examples of the man Command

1. Read the manual page of a specific command.

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   $ man ls
   

   The above command displays the manual page for the ls command, which includes detailed information about its usage.

   Output:

   

2. Search for a command using a specific keyword in its description.

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   $ man -k copy
   

   The above command looks up a command's short description or manual page names with the keyword copy and lists all related commands.

   Output:

   

3. Display manual page titles.

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   $ man -f ls
   

   The above command displays the titles of manual pages for the ls command with a brief description for each.

   Output:

   

4. View all the manual pages for a specific command.

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   $ man -a intro
   

   The above command displays all manual pages for the intro command.

   Output:

   

5. Display the location of manual page files.

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   $ man -w ls
   

   The above command outputs the path to the ls manual page.

   Output:

   

6. Use man with a custom pager command.

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   $ man -P cat ls
   

   The above command uses cat instead of the default pager to display the ls manual page.

   Output:

   

7. Specify a manual page section to look up a specific command.

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   $ man 5 passwd
   

   The above command displays section 5 of the passwd manual page that includes the file format information.

   Output:

   

Navigating the Manual Pages

Use the following keyboard shortcuts to navigate and search through the manual page contents.

• Spacebar: Scroll down one screen at a time.
• b: Scroll up one screen at a time.
• Enter: Scroll down one line at a time.
• k: Scroll up one line at a time.
• /pattern: Search forward for a pattern.
• ?pattern: Search backward for a pattern.
• n: Repeat the last search in the same direction.
• N: Repeat the last search in the opposite direction.
• q: Quit the manual page viewer.

Understanding Manual Page Sections

Manual pages are divided into sections that include different types of information. Common sections include:

• 1: User commands.
• 2: System calls.
• 3: Library functions.
• 4: Special files (usually found in /dev).
• 5: File formats and conventions.
• 6: Games and screensavers.
• 7: Miscellaneous.
• 8: System administration commands.

Advanced Usage Scenarios

1. View the manual pages for library functions.

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   $ man 3 printf
   

   The above command displays the manual page for the printf function, which is part of the C standard library.

   Output:

   

2. Read the manual pages for system calls.

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   $ man 2 open
   

   The above command displays the manual page for the open system call and provides information on how files are opened in the kernel.

   Output:

   

3. Use man in scripts to display specific documentation information about commands.

   • Create a new script file using a text editor such as Nano

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     $ nano my_script1.sh
     

   • Add the following contents to the file.

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     #!/bin/bash
     echo "Displaying the manual page for the 'ls' command:"
     man ls
     

   • Enable execute permissions on the file.

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     $ chmod +x my_script1.sh
     

   • Run the script

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     $ ./my_script1.sh
     

   The above script displays the manual page for the ls command when executed.

   Output:

   

4. Combine the man command with grep to search pages.

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   $ man ls | grep "list"
   

   The above command pipes the manual page output for the ls command to grep and search for lines that contain the string list.

   Output:

   

5. Update the manual pages database.

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   $ sudo mandb
   

   The above command updates the database of all manual pages to ensure new or removed pages are available in the search results.

Conclusion

You have used the man command to search for documentation and command usage pages. For more information about the man command, run man man to view the command's manual page.