Beginner Lab 1 - Unix, the Shell, OSS

Welcome to the first lab! Here are some commands you might find helpful: cat, cd, emacs, file, grep, less, ls, man, nano, tar, wget, vim

Remember: Google and man are your friends!

Shell spelunking

Everything should be done via the shell!

The purpose of this lab is to get you comfortable with using the shell for things you might typically use a GUI for. While these tasks may seem simplistic or limited, you’ll quickly find that the commands have many different options (flags) to perform tasks that are either impossible or incredibly tedious / difficult to complete using traditional methods.

1. ssh into tsunami.ocf.berkeley.edu using your OCF account, or login at ssh.ocf.berkeley.edu

2. Run the following command to download the file we have provided: wget https://decal.ocf.berkeley.edu/static/b1/b01.tgz

   A .tgz file is actually a composition of two file formats. Sometimes you’ll see these files as .tar.gz instead. A common (and old) way of archiving is with magnetic tapes. However, in order to archive the data, it needs to be a single file, and often you want to archive multiple files at once. This is where the tar command comes in (tar stands for tape archive). Tar will group (or ungroup) multiple files into a single one.

   tar, unless you ask it to, doesn’t compress files itself though. This is where either gzip (or bzip2) comes in. gzip will compress your file, and so, tar + gzip is often used in conjunction. It looks something like this: file --(tar)--> file.tar --(gzip)--> file.tar.gz.

   If you read the tar documentation carefully enough, you’ll see that you can give the command an option to compress your files using gzip as well, saving you a total of one line of shell command!

   To unarchive the file we provide you, run the following command: tar xvzf b01.tgz. This will provide a b01 directory for you with some files for the rest of this lab.

   tar has a reputation for being a bit tricky with its options:

3. Go into the b01 directory. Make sure you’re in there by running pwd (Present working directory). What does pwd give you?

4. There’s a hidden file in the b01 directory. What is the secret?

5. A malicious user made its way into my computer and added a bunch of nonsense files. What do the files say? (Hint: They all have the same contents). Help me get rid of them by deleting all of these files and the directory they are in.

6. There’s a file in b01 called big_data.txt. It’s 80 megabytes worth of random text. For reference, Leo Tolstoy’s “War and Peace”, the novel with a whopping 57,287 words depicting the French invasion of Russia and the impact of the Napoleonic era on Tsarist society through the stories of five Russian aristocratic families with several chapters solely dedicated to philosophical prose, is only 3.2 megabytes large.

   For that reason, I don’t recommend using cat to print the file. You can try it, but you’ll be sitting there for a while. There’s some text you need to find in there! Go find it without actually opening up the file itself! (Hint: It’s a url)

   Two lines above the URL is a secret solution. What is that solution? Hint for this one: “Context Line Control”

7. There’s a file called trojan_horse.txt. Try reading it using less. Surprise! It’s not a text file. Find out what kind of file it is.

8. Finally, there’s an empty file called hello_world in the directory. Write your name in it!

9. Once you’re done remember to fill out the Google form. There’s some other questions you’ll have to answer and some feedback we’d like you to fill out!