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[MUSIC]

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Hi, I'm Kenneth.

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And in this course I'm going to show you
how to use Python to take control of

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the files and directories on a computer.

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By the end of the course, you'll be able
to use Python to check the size of files,

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create new files,
rename directories, and more.

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Why would you want to use Python to do
tasks that you normally do with your

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operating system's file explorer?

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Occasionally, you'll find yourself working
on a system where you don't have any sort

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of visual file explore, like looking on
a server or a microcontroller device.

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Or maybe you have a repetitive
task like creating of files and

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directory structure for a project.

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And you're just sick and
tired of doing it by hand.

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And even if none of that applies to you,
knowing more about Python and

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how to use it for
tasks like this is never a bad thing.

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This situations pop up when
you least expect them.

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Before we get into the Python tools, and
libraries and code, I want to take a few

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minutes to make sure your familiar with
the terms we'll be using in this course.

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While I'm sure some of you
are comfortable with these terms,

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it never hurts to have
a bit of a refresher.

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Computers typically store data in files,
whether these are text documents, images,

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movies or databases.

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Files have two major parts,
their filename and their file type.

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Most of the time, the file type is
reflected in the extension part of

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the filename, which is the part that
comes after the dot in the filename.

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For example, a very common image
format is the JPEG format.

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Most JPEG files have
a .JPG file extension,

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which tells you that it is a JPEG file.

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The file extension, for

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the most part though,
is just extra information for humans.

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Computers and software would use the file
type, and not the extension to identify

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what kind of file a file is, when it
needs to display or modify the file.

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Files are stored in Directories.

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It's become common parlance to
call directories folders, and

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we usually have an icon of
a folder to indicate them.

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But the actual name is directory.

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I will do my best to stick to using
directory, but if I slip up, forgive me.

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Directories often form a tree of sort,

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with directories nested
inside of directories.

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If I trace the directory tree
all the way back though,

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I'll eventually come to the root
directory, or location.

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On Windows,
this is usually a drive name, like C.

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On a POSIX system, like Linux, Unix,

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or Mac OS through, It would be just
a single slash that leans to the right.

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I'll use backslash for slashes that
lean to the left like on Windows.

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And forward slash, or just slash for
ones that lean to the right.

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When we talk about the location
of a single directory or

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file, we call this collection of
directory and file names its path.

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For example, if I have a file named
my_next_course.py in my user's directory,

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it might have a path like this,
C:\Users\Kenneth\my_next_course.py.

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Actually, let's talk about those slashes
for a second, the official word for

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them is separators.

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On the Windows systems the slashes between
directory and file names lean to left,

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every where else though
they lean to the right.

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We call slashes that go
to the left blackslashes,

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and those that go to the right
forwardslashes or just slashes.

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If your typing out paths on these systems,
be sure to use the correct slash.

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Python provides a system aware item
named SEP, S-E-P, in the OS module

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to help you with this, but I'll show you
how you can avoid dealing with it at all.

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In fact, we'll be using the OS library for
most of this course.

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But like many Core Python modules
the OS module is huge, and

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we won't be covering all of
it in just this one course.

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If you're not comfortable moving
around in your file system,

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check the teacher's notes for
a link to our Console Foundations course.

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Otherwise, I think it's time to start
looking at the tools we'll use to prune

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and grow our file tree.