The Command Line

Each operating system has a different set of commands and different ways to access the command line. The instructions below should work for bash using systems like Mac OS X, Linux, and other Unix-ish operating systems.

For Windows users, the easiest way to follow the guide is to download a bash terminal like Cygwin.

In Mac OS X, access to the command line is through a program called Terminal.app, which is always installed in the Utilities folder, inside Applications.

cd

Changing directories using the command line is done using the cd command, which stands for change directory. This is followed by a space then the directory you would like to move into.

This looks like this:

$ cd Documents

In this case we would like to change directories to the Documents folder. The $ represents the command line prompt. When inputting commands, you do not include the $. The first part of this command is cd, which is the change directory command. This is followed by Documents, which is the directory we would like to change into.

pwd

When you hit enter to input the command, depending on your command line set up, nothing will appear on the screen. To check which directory you are in, you can use the pwd command, which stands for print working directory, in other words the folder you are currently in.

In this case, it would look like this:

$ pwd
/Users/your-username/Documents

This shows the full path for your current directory.

If you wish to go up a level to the previous or enclosing directory, you also use the cd command, but you do not need to input a directory name. In the command line . represents your current directory and .. represents the parent directory.

To change to the parent directory you can enter the following:

$ cd ..
$ pwd
/Users/your-username

If you then enter pwd it will show you that you are back in your home directory.

ls

If you want to know the contents of a given directory, you can use the ls command, which stands for list directory. When you enter ls it will show you all the files and directories that are contained within your current directory.

This looks like the following:

$ ls
Applications  Desktop  Documents  Downloads  my_thesis.txt

This is helpful for determining what is in your current directory.