The Unix Command Line

In the days before graphical user interfaces (GUI), computers were operated by entering commands to a prompt in the terminal. It’s a text interface for keyboard entry (no mouse). You can perform almost all the same tasks as that can be done on GUI.

Today, it is still important to know how to use the unix command line if you're working with cloud computing.

Commands

Many of the commands are one word in lowercase such as the following:

• cat: shows the contents of a file, all at once
• more: shows the contents of a file, screen by screen
• less: also shows the contents of a file, screen by screen
• head: used to show so many lines from the top of a file
• tail: used to show so many lines from the bottom of a file
• script: used to record commands and their output

Read more:

• https://www.learnenough.com/command-line-tutorial/basics
• http://conqueringthecommandline.com/book
• http://man7.org/linux/man-pages/man1/script.1.html
• https://swcarpentry.github.io/shell-novice/reference/

Featured Commands

• grep
• sort cat foo.txt | sort with -n numeric sort or -r reverse sort
• comm to compare using set operations
• uniq to find unique lines
• cat lets you concatenate multiple files