Command Line

Why the Command Line?

Some students struggle a bit with using the command line at first. And that's totally natural; for someone who's always used a graphical interface, the command line may seem complex and non-intuitive (not to mention dated and slow).

And while text-based interfaces were the original interface to computers (well, not counting punch cards), and they are somewhat complex, almost everyone who sticks with using the command line finds it to be faster, more efficient, and even natural after a while.

We'll be using the command line quite a bit in this course, so it's important that you start getting comfortable with it.

##General Concepts The command line (or 'terminal') is an interface for issuing commands to your computer, and viewing the results. It is entirely text-based.

Commands are almost always a single line in length. When you hit 'enter' after typing a command, the computer runs the command, and any output is displayed.

Commands consist of the command, followed by any arguments that modify the commands behavoir. For example, on a Mac/Linux, I can issue the following two commands

• ls
• ls -a

In both cases, I'm running the command ls, which lists the files in the current directory. But in the second case, I've added the arguement -a, which tells ls to show all files, even hidden ones.

When you're using the command line, your always working in the context of a directory on your computer. In example above, that's important, so my computer knows which directoy to list the contents of. If I want to see the contents of a different directory, I need to change directory (see command list below)

##Common Commands (Mac / Win / Linux)

• cd some_directory - change current working directory to some_directory (which must be in the current directory)
• cd .. - '..' has a special meaning, the parent directory of the current one. So this takes you up one level.
• mkdir new_folder_name - make a new directory in the current directory

##Mac/Linux Specific

• pwd - list the current directory
• ls - list files and folders in the current directory
• rm some_file - deletes some_file (add -r to delete folder, i.e. rm -r some_folder)