The unique and invaluable command line interface (CLI) is a tool that I've come to realize I can't live without. Contrasting with the graphical user interface (GUI), which requires the use of a mouse pointer to click on options, the CLI mechanism for interacting with a computer operating system or software involves typing commands to perform specific tasks.
The more efficient CLI is a bit like a 'macro on steroids.' It is used whenever a large vocabulary of commands or queries, coupled with a wide or arbitrary range of options can be entered more rapidly with text than with a pure GUI. A GUI uses windows, icons and menus to carry out commands such as opening files, deleting files, moving files, etc. Many GUI operating systems are operated by using a mouse, although the keyboard can also be utilized with shortcuts or arrow keys. While GUIs can be easily picked up for new users with its simpler format, CLIs require a bit more memorization and familiarity in order to successfully navigate and operate the interface. However, once a user has this familiarity down, there are massive benefits to the CLI that make it, in my – and Neal Stephenson's -- opinion, more efficient than its graphical opposition. (Although, there are those who disagree.) Advanced CLI users need only to execute a few lines on their keyboard to perform a task, so they are able to get tasks done much faster than even an advanced GUI officer. The CLI interface also enables a user to easily script a sequence of commands to perform a task or execute a program, and while GUIs can allow users to create shortcuts, the graphical interface doesn't even come close in comparison to the 'macro on steroids' effect that a command line has.
While I prefer the CLI, those who are more visual people or prefer a more 'user-friendly' system will likely lean toward a graphical user interface. The important thing is to determine what exactly is the task you are trying to accomplish, and consider both options when deciding which interface would be best for you.
About the Author: Curt Finch is the CEO of Journyx (http://pr.journyx.com), a provider of web-based time tracking, project accounting and resource management software designed to guide customers to per-person, per-project profitability. Curt earned a B.S. in Computer Science from Virginia Tech in 1987 and he has been creating software or managing software teams ever since. An avid speaker and author, Finch's book, 'All Your Money Won't Another Minute Buy: Valuing Time as a Business Resource' is available in most online bookstores. He is also a blogger for Inc. (http://www.inc.com/tech-blog), and you can follow him on Twitter @clf99. Curt can be contacted at email@example.com.