website/content/csci2000/Tutorial01.md

+++ date = "2020-09-12" title = "Tutorial 01 - Getting start with Jupyter Cloud and Linux"

+++

1. Getting to know Jupyter Cloud

When you first log in you will be asked to log in with your Google account. Please log in with your @ontariotechu.net account.

Then click the course code (csci2000) to go to your dashboard.

Finaly click on 'Start My Server' and confirm by clicking 'Launch Server'

{{< center >}} VVVVVVVV {{< /center >}}

This may take a few moments. Especially if a lot of students are trying to access Jupyter Cloud at the same time. Once you are done you should see the main file browser.

From here we can:

• Browse the file system
• create and edit text files
• create and edit Python3 notebooks
• launch a terminal emulator

If we click 'New' in the top right we see the option to create new notebooks, files, folders, or terminals.

Notebooks are where we can write code and execute it. This can be done in chunks or cells. Writing spreading our code over multiple cells allows us to execute them separately and verify the output of one chunk before we continue. We can also modify and execute a cell again if we need to modify something. A cell can can contain code or formatted text. You can format text using Markdown. Using and formatting Notebooks will be discussed in greater detail in future tutorials.

The terminal allows use to use a Bash shell to manage our instance and manipulate files. This is far more powerful then a visual file manager at working with multiple files at a time. From here we also have access to many other useful commands for exploring, editing or finding files. As well as, looking at running and managing processes, checking disk and memory usage. A lot of useful commands will be discussed in this weeks and next weeks tutorials.

Terminals and Notebooks will run in the background. To see what is still running you can use the 'Running' tab from the main page. On this tab we can also shutdown any of the running Jupyter processes.

2. Getting started with the command line

When you start a new terminal in Jupyter Cloud, it spawns a Bash shell. Bash is a very common Linux command line environment. A lot of what you'll learn here will transfer to other Linux distributions such as Ubuntu, Fedora, or Arch. This tutorial only covers some of the basics but we will learn more about the power of Bash and the Linux command line throughout the semester.

First we can check the current time and date with the date command:

df tells us our current disk usage:

free tells us our current memory usage:

If we want to rerun a previous command, we can use the arrow keys to navigate our command history. UP goes backward and DOWN goes forward.

Lastly, we can end a session with the command exit. Note: this does not close the window but we cannot run any more commands

3. Navigating the file system

Let's discus the basics of navigating the file system in a command line environment. We can't click or drag 'n drop files around but that doesn't mean we can't do anything. As a matter of fact we have more powerful tools for working with multiple files and doing task such as bulk renaming, or automating repeated tasks.

First let's get our bearings. pwd will let us know where we are located.

As we can see, we are currently in /home/jovyan. We can now use ls to list the files in this directory/folder.

We can now see that this directory contains one thing: another directory called 'work'. We can use cd to change directories to this new directory. If we repeat the previous stop we can see that this directory is the same as the one we can access through Jupyter Cloud's file browser. All work done with Jupyter Cloud will be placed under this directory.

We need to specify cd the path to the directory we want. In our example we wanted work. This is a relative path, meaning relative to our current directory. So the absolute path to the same directory would be /home/jovyan/work/. All absolute paths start with / meaning the root (or top) of the file system. We could have also supplied cd with an absolute path.

Similarly ls allows us to select which directory we want listed. By default it will print the files in our present working directory (pwd) but if we pass /home/jovyan as and argument we get a different output. If we wanted to print multiple folders we can do that as well. Plus we can mix and match absolute and relative paths.

There are also a few shortcuts we can use:

• -

• the previous directory
  • similar to the back button in Windows File Explorer
  • this is useful if we want to go back

• ..
  • up one directory

• similar to the up button in Windows File Explorer

• .
  • the current directory
• ~

• our home folder

• ~<user>

• the home folder of the specified user
  • ie ~jovyan for our home folder

Most programs have a set of options and arguments that modify their behaviour. Usually specified in the order command -options arguments. For ls, the argument is the directory you want listed. There are also a number of very useful options:

Long Version	Short Version	Description
--all	-a	show all files, including hidden files
--directory	-d	show detail about directory instead of contents
--classify	-F	append indicator to end of name (displays file type)
--human-readable	-h	display file size in human readable format instead of bytes
-l	display in long format
--reverse	-r	display in reverse alphabetical order
-S	sort by file size
-t	sort by modification time

Note that some of these have both long and short versions. You can use either.

Let's take a look at the long format for ls:

Field	Description
-rw-rw-r--	file type and permissions in order: type user(rwx) group(rwx) world(rwx)
1	number of hard links to file
jovyan	username of owner
jovyan	name of group owner
834	file size in bytes
Sep 13 18:01	timestamp of last modification
'Hello World.ipynb'	file name

We can look at the contents of a file using the less command. If we use it to look at the contents of a .ipynb file we will get something that looks like this:

You can navigate the file while in less. Here is a chart of the commands:

Command	Action
PAGE UP or b	scroll up one page
PAGE DOWN or SPACEBAR	scroll down one page
UP ARROW	scroll up one line
DOWN ARROW	scroll down one line
G	go to end of file
1G or g	go to begining of file
/<sequence>	search for next occurance of <sequence>
n	search for next occarance of previous search
p	search for next previous of previous search
h	display help
q	quit