Reading Files

There are a number of commands you can use to quickly read the contents of a file without having to open the file in a text editor. But, for now:

1. Create a file on your Desktop called lorem.txt and open it in your favourite plain-text editor.
2. Copy the following text into the file and save it.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Fusce imperdiet maximus ipsum id iaculis.
Morbi ultrices quam et ullamcorper ullamcorper.
Vivamus dignissim nisl quis purus volutpat, eget rhoncus libero pulvinar.
Sed pretium dignissim ex, in sollicitudin ex suscipit nec.
Sed aliquet tempus nunc, ut vestibulum lacus placerat vel.
Sed auctor interdum diam non feugiat.
Suspendisse nec pellentesque mi, et elementum sem.
Aenean eu diam dui.
Vivamus a pretium diam, eget tempor tellus.
Cras gravida ligula orci, quis sodales dui fringilla eget.
Vestibulum varius consectetur volutpat.
Aliquam scelerisque non metus quis molestie.
Mauris quis convallis eros.
Proin maximus erat at urna consectetur pharetra.
Aenean tempus molestie arcu, id laoreet sem imperdiet id.
Etiam eu neque sed ante eleifend elementum.
Sed ac ex mi.
Cras ut mi nisi.
Nulla ac enim magna.
Nullam molestie ligula ultrices posuere aliquet.
Ut nec pulvinar nisl.
Suspendisse tempor arcu sed odio faucibus convallis.
Ut condimentum feugiat quam, a fringilla velit sodales vitae.
Morbi ultrices eros at lacus posuere, sit amet sollicitudin dolor sollicitudin.
Maecenas et urna sagittis, auctor est eget, sollicitudin nulla.
Phasellus commodo orci diam, et pulvinar sem pulvinar cursus.
Sed pretium enim ac urna feugiat, at ullamcorper est sodales.
Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Now, back to your terminal, you can attempt to read the contents of this file using 2 different commands:

The first one is the less command:

less lorem.txt

This opens a preview of the file in your terminal. You can scroll up and down using your keyboard. When you're done, press q to quit and go back to your terminal.

The second one is the cat command:

cat lorem.txt

Which prints the contents of the file to the terminal directly.

Note: This command actually has more uses than just reading files - it is short for concatenate, and is used mainly for joining the contents of two files together.

Did you know you can be quite specific about what to print from the file?

head lorem.txt Will show you the first 10 lines of the file.

tail lorem.txt Will show you the last 10 lines of the file.

If you want to see more or less than the default 10 lines, you can pass the number in as a switch.

tail -3 lorem.txt Will print the last 3 lines and the same would work with head.

Another note, because we love them:

tail also has a cool feature where it will keep watching a file for any new content added to the end.

If you are on a Mac run the following command: tail -f /private/var/log/system.log

This is a log file of some of the processes that your computer is running. If you open or close an application (just open a new browser window, for example), you should see the output being updated. This can be a useful tool when you are running a program and want to see what's happening internally.

To stop following the log file, just use ctrl + c.