What Means In Unix

Shell Programming

In the world of Unix, the what command holds a special place in my heart. It may seem like a simple command, but its power and versatility make it an essential tool for any Unix user. So, what exactly does what mean in the realm of Unix? Let me dive deep and explain it to you.

At its core, the what command is used to display information about a given Unix command or file. It allows you to quickly gather details about the purpose, functionality, and usage of a specific command without having to navigate through the mountains of Unix documentation. It’s like having a knowledgeable companion by your side, ready to provide you with insights and guidance.

One of the aspects that make the what command so handy is its ability to provide concise and organized information. When you execute what followed by the name of a command, it will display the command’s name, location, and a brief description. This brief description can be a real lifesaver when you encounter a new command and want to understand its purpose without spending too much time searching for documentation.

Let’s take an example. Suppose you come across the command grep in a script or on a Unix forum and want to know what it does. By simply typing what grep in the terminal, you will get a clear overview of the command’s functionality:

$ what grep
grep(1) - file pattern searcher and manipulator

From this simple output, you can gather that grep is a command used to search for patterns in files. The “(1)” next to the command indicates that it belongs to the section 1 of the Unix manual, which typically covers user commands. Armed with this knowledge, you can now explore further or use the command confidently in your own scripts.

Not only does the what command provide a brief description, but it also offers additional information in some cases. For commands that have variations or multiple implementations, what can show you a list of related commands. This is especially useful when you are trying to figure out which specific version of a command is available on your Unix system. You can simply run what followed by a command and get a list of alternatives.

In addition to commands, the what command can also provide information about files. If you are curious about a particular file’s purpose or origin, you can use what followed by the file name to get details about it. This can be helpful when you stumble upon unfamiliar files or need to investigate the source of a file on your system.

To summarize, the what command is a versatile and practical tool in the world of Unix. It allows you to quickly gather information about commands and files, making it easier to understand their purpose and usage. Whether you are a seasoned Unix user or just starting out, what can be a valuable resource to have in your toolkit.


The what command may seem simple on the surface, but its ability to provide concise and organized information about Unix commands and files makes it a powerful tool. With what by your side, you can easily explore and understand the vast world of Unix without getting lost in the sea of documentation. So, next time you come across an unfamiliar command or file, don’t hesitate to turn to what for guidance.