How to use the command 'whatis' (with examples)

The whatis command is an essential tool within the Unix-like operating systems, designed to provide users with quick and concise descriptions of system commands. By leveraging a database of short command descriptions, whatis enables users to swiftly locate the relevant information about commands they are interested in. This is particularly useful for both newcomers and seasoned users who need to recall the purpose of various commands without diving into lengthy man pages. The command searches for the provided keywords and returns descriptions if matches are found in the database.

Use case 1: Search for information about a single keyword

Code:

whatis keyword

Motivation:

Imagine you’re familiarizing yourself with Linux commands and encounter a command name that sounds unfamiliar or you can’t recall its exact purpose. Instead of sifting through lengthy and technical man pages or complex online resources, you can use the whatis command. This command provides a swift and straightforward description of the keyword you’re curious about, helping you rapidly glean an understanding of its basic functionality.

Explanation:

• whatis: This initiates the command itself, indicating the user’s request for a brief description from the system’s database.
• keyword: This is the user-specified term representing the command or topic you want information about. For instance, if you enter ls, the system will look for and return the short description of the ls command.

Example Output:

If you input whatis ls, you might receive feedback like:

ls (1)               - list directory contents

This gives a concise yet informative description of what the ls command does, sparing you the need to delve further unless you wish to.

Use case 2: Search for information about multiple keywords

Code:

whatis keyword1 keyword2

Motivation:

This use case is particularly beneficial when you are examining a group of commands, perhaps as part of learning or troubleshooting. Being able to obtain descriptions for multiple commands at once can significantly accelerate the learning process, enabling a user to efficiently cross-reference functionalities and decide which commands to explore in greater depth. It is also useful when performing script reviews or updates, where multiple command functionality needs clarification.

Explanation:

• whatis: The central command invoking the search for descriptions.
• keyword1 keyword2: By listing multiple keywords separated by space, you request the whatis command to perform searches on each separately. This batching process maximizes efficiency by reducing the need to repeat the command multiple times for different commands.

Example Output:

Inputting whatis ls cp might return:

ls (1)               - list directory contents
cp (1)               - copy files and directories

This output gives you an immediate insight into both the ls and cp commands, simultaneously helping to understand that ls is used for listing directory contents while cp is used for copying files and directories.

Conclusion:

The whatis command is a powerful utility for Unix-like system users who need quick references on system commands. By utilizing simple keyword queries, users can save time and reduce potential confusion associated with commands whose functionalities they may not fully understand. Whether for single or multiple keyword inquiries, whatis enriches the command line experience, making it a valuable component of any user’s toolkit.