Mastering the 'man' Command (with examples)

The ‘man’ command is an essential tool in Unix-based operating systems, providing users with comprehensive documentation on various commands, system calls, library functions, and more. It formats and displays manual pages, allowing users to better understand how to use different features of the system. These manual pages are divided into sections, each covering different aspects of the system, from basic user commands to detailed programming functions.

Display the man page for a command

Code:

man command

Motivation:
When you’re trying to learn about a new command or need a refresher on a command’s functionalities, accessing its manual page is crucial. The ‘man’ command, followed by the command name, provides detailed information about its uses, options, and examples.

Explanation:
The argument command is the specific command you wish to learn about. ‘Man’ will retrieve the corresponding manual page, offering insight into how the command is employed within the operating system.

Example Output:

NAME
    ls - list directory contents

SYNOPSIS
    ls [OPTION]... [FILE]...

DESCRIPTION
    List information about the FILEs (the current directory by default) ...

Display the man page for a command from section 7

Code:

man 7 command

Motivation:
Commands in Unix can have multiple manual pages spread across different sections. For example, ‘printf’ can have a shell built-in command manual and a library function manual. Knowing the section is important when you want information related to a specific aspect of the command.

Explanation:
The number 7 refers to the section from which you want to access the manual. Section 7 typically contains information about macro packages and conventions. The command following the section number is what the manual page will focus on.

Example Output:

CONVENTIONS(7) Linux Programmer's Manual CONVENTIONS(7)

NAME
     conventions - Linux kernel coding conventions

List all available sections for a command

Code:

man -f command

Motivation:
Sometimes, understanding the full scope of information available for a command across different sections is beneficial. This is especially true when a command has implementations that pertain to different facets of the system.

Explanation:
The -f option tells ‘man’ to list all sections for the given command. It stands for “whatis” and provides a quick summary or index for the command in different sections.

Example Output:

printf (1)            - format and print data
printf (3)            - formatted output conversion

Display the path searched for manpages

Code:

man --path

Motivation:
Knowing where the system searches for manual pages is useful for troubleshooting and customization purposes. For administrators, it helps in managing paths and ensuring that manpages are correctly placed.

Explanation:
The --path option queries the system and displays the directories it checks for available manual pages. This doesn’t require additional arguments as it refers to the system’s global settings.

Example Output:

/usr/share/man:/usr/local/share/man

Display the location of a manpage rather than the manpage itself

Code:

man -w command

Motivation:
At times, you may need to know the file location of a manpage directly, especially if you are editing or auditing documentation. Finding the location allows one to navigate to and, if needed, modify the correct file.

Explanation:
The -w option tells ‘man’ to provide the path to the manual page for the specified command, rather than displaying its contents. This is helpful for directly accessing the file system location.

Example Output:

/usr/share/man/en/man1/ls.1.gz

Display the man page using a specific locale

Code:

man command --locale=locale

Motivation:
For users who prefer or require documentation in a language or locale other than the default set on their system, this option is indispensable. It allows reading manuals in the most understandable form for the user.

Explanation:
The --locale=locale option specifies the locale you wish the manual page to be displayed in. Replace locale with the desired language setting, such as en_US for American English.

Example Output:

(Let's assume the system's locale is set for English but you're accessing a French translation)
DESCRIPTION
     Liste les informations sur les fichiers (répertoires actuels par défaut)...

Search for manpages containing a search string

Code:

man -k "search_string"

Motivation:
When you are not sure about the exact command needed but have an idea of what it should relate to, this search feature becomes handy. It helps find relevant commands or topics swiftly without going through generic searches.

Explanation:
The -k option is for search, and "search_string" is the phrase or word you are investigating. ‘Man’ will cross-reference this against its index of available manpages and return related entries and sections.

Example Output:

grep (1) - print lines that match patterns
fgrep (1) - grep searching with fixed strings

Conclusion:

The ‘man’ command is an indispensable tool in any Unix-based environment. By following these use cases, users can effectively tap into the wealth of information stored in their system’s manual pages, ensuring they make the most out of their systems. Whether you’re troubleshooting, learning, or just exploring, mastering these functionalities can significantly enhance your command-line proficiency.