Introduction to Shell

The Unix command line helps users combine existing programs in new ways, automate repetitive tasks, and run programs on clusters and clouds.

The Unix command line has survived and thrived for almost 50 years because it lets people do complex things with just a few keystrokes. Sometimes called "the universal glue of programming," it helps users combine existing programs in new ways, automate repetitive tasks, and run programs on clusters and clouds that may be halfway around the world. This course will introduce its key elements and show you how to use them efficiently.

• Manipulating files and directories
• This chapter is a brief introduction to the Unix shell. You'll learn why it is still in use after almost 50 years, how it compares to the graphical tools you may be more familiar with, how to move around in the shell, and how to create, modify, and delete files and folders.
• Manipulating data
• The commands you saw in the previous chapter allowed you to move things around in the filesystem. This chapter will show you how to work with the data in those files. The tools we’ll use are fairly simple, but are solid building blocks.
• Combining tools
• The real power of the Unix shell lies not in the individual commands, but in how easily they can be combined to do new things. This chapter will show you how to use this power to select the data you want, and introduce commands for sorting values and removing duplicates.
• Batch processing
• Most shell commands will process many files at once. This chapter shows you how to make your own pipelines do that. Along the way, you will see how the shell uses variables to store information.
• Creating new tools
• History lets you repeat things with just a few keystrokes, and pipes let you combine existing commands to create new ones. In this chapter, you will see how to go one step further and create new commands of your own.