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The Insider's Guide to Accessing NLM Data

What is Unix?

As new Insider's Guide classes are no longer being offered, this site is not currently being updated. Please refer to NCBI's E-utilities documentation for more up-to-date information.

What is Unix?

Unix is an operating system that allows you to interact directly with a computer. Unix was developed in the 1970s, but is still in widespread use today, especially on servers and other high-powered machines. You can use Unix to interact with a computer via a command-line interface: users are presented with a text prompt, enter commands, and execute them. You may also see the Unix command prompt referred to as a “shell”, a “terminal” or a “terminal emulator”. These terms do not all mean exactly the same thing, but the distinctions between them are not relevant to this discussion.

Modular design and Unix

Unix was built on the idea of “modular design”: each Unix tool or command is designed to do only one thing, but to do that one thing very well. Over time, however, developers who have their own personal tastes have developed different tools and programs to do almost the same thing, but in slightly different ways. This means that there are often multiple different ways in Unix to do the same thing, so there are often many “right” answers, and many options for users.

Creating scripts in Unix

Because each Unix tool or command only does one thing, you will often want to combine a series of commands together in sequence, using the output of one as the input for the next. Unix is really built around this idea, and facilitates the use of “scripts”, which are basically mini-programs that combine sets of commands together. To learn more about combining commands together into scripts, see Working with Unix.

How to get started

In order to use Unix, you will need access to a Unix command-line terminal emulator (or “Unix terminal”, for short). Some operating systems (like Linux and macOS) have a Unix terminal built-in. For other operating systems, like most versions of Microsoft Windows, you can install a third-party terminal emulator (such as Cygwin). For more information about installing Cygwin, see our Installing EDirect page.

Last Reviewed: July 30, 2021