Navigating the command line

Keyboard Shortcut	Meaning
Arrow up/down	Go backwards/forwards in the history of previously executed commands
Tab key	Autocomplete directory or file names
Ctrl + C	Cancel whatever program is currently running in the command line
Ctrl + D	Exit IRB or command line

General commands

These commands are useful, no matter whether you work with Ruby or not.

These are of the most important commands on the command line. You have seen all of these in the slides already, but here’s a nice overview:

Command	Argument(s)	Meaning	Description
pwd	None	“print working directory”	Shows the current working directory of your command line
ls	Directory name (optional)	“list directory contents”	Lists all files and directories in a directory
cd	Directory name (optional)	“change directory”	Changes the current working directory of your command line

Here are some example usages with a description what they mean:

Command	Meaning
ls	List what is inside the current working directory (files and directories).
ls my-directory	List what is inside my-directory, which is a directory in the current working directory.
ls ~	List what is inside the current user’s home directory.
cd my-directory	Change the working directory to my-directory, which is a directory in the current working directory.
cd cd ~	Change the working directory to the current user’s home directory.
cd ..	Change the working directory to the current working directory’s parent directory.

Ruby-specific commands

These commands are only used for programming Ruby, not with other programming languages.

Command	Argument(s)	Meaning	Description
ruby	program file name		Runs code that was saved to a .rb file previously.
irb		“interactive Ruby shell”	Starts IRB, which is a quick way to play around and try things in Ruby, without having to save your code to a file.

For example, if you want to run the Ruby code in your file hello.rb, run this in the command line: ruby hello.rb. Make sure that you’re in the directory which contains the file you want to run first (see ls and cd)!