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Another foundational command that's good to know is 
touch
, which actually serves 
two purposes. First, assuming you have permission to do so in your current working 
directory, the 
touch
 command will create an empty file if it doesn't already exist. 
Second, the 
touch
 command will update the modification time of a file or directory if 
it does already exist:
Figure 4.4: Experimenting with the touch command
To illustrate this, in the related screenshot, I ran several commands. First, I ran the 
following command to create an empty file:
touch testfile.txt
That file didn't exist before, so when I ran 
ls -l 
afterward, it showed the newly 
created file with a size of 0 bytes. Next, I ran the 
touch testfile.txt
 command 
again a minute later, and you can see in the screenshot that the modification time 
went from 
15:12
 to 
15:13
.
When it comes 
to viewing the contents of a file, we'll get to that later on in this 
chapter. And there are definitely more commands that we'll need to learn to build 
the basis of our foundation. But for now, let's take a break from the foundational 
concepts to understand the Linux filesystem layout better, which is pretty much 
mandatory for some of the commands we'll learn later.