Appendix. Command Line Crash Course
This appendix is a super fast course in using the command line. It is intended to be done rapidly in about a day or two, and not meant to teach you advanced shell usage.
Introduction: Shut Up and Shell
This appendix is a crash course in using the command line to make your computer perform tasks. As a crash course, it’s not as detailed or extensive as my other books. It is simply designed to get you barely capable enough to start using your computer like a real programmer does. When you’re done with this appendix, you will be able to give most of the basic commands that every shell user touches every day. You’ll understand the basics of directories and a few other concepts.
The only piece of advice I am going to give you is this:
Shut up and type all of this in.
Sorry to be mean, but that’s what you have to do. If you have an irrational fear of the command line, the only way to conquer an irrational fear is to just shut up and fight through it.
You are not going to destroy your computer. You are not going to be thrown into some jail at the bottom of Microsoft’s Redmond campus. Your friends won’t laugh at you for being a nerd. Simply ignore any stupid weird reasons you have for fearing the command line.
Why? Because if you want to learn to code, then you must learn this. Programming languages are advanced ways to control your computer with language. The command line is the baby brother of programming languages. Learning the command line teaches you to control the computer using language. Once you get past that, you can then move on to writing code and feeling like you actually own the hunk of metal you just bought.
How to Use This Appendix
The best way to use this appendix is to do the following:
• Get yourself a small paper notebook and a pen.
• Start at the beginning of the appendix and do each exercise exactly as you’re told.
• When you read something that doesn’t make sense or that you don’t understand, write it down in your notebook. Leave a little space so you can write an answer.
• After you finish an exercise, go back through your notebook and review the questions you have. Try to answer them by searching online and asking friends who might know the answer. Email me at [email protected] and I’ll help you too.
Just keep going through this process of doing an exercise, writing down questions you have, then going back through and answering the questions you can. By the time you’re done, you’ll actually know a lot more than you think about using the command line.
You Will Be Memorizing Things
I’m warning you ahead of time that I’m going to make you memorize things right away. This is the quickest way to get you capable at something, but for some people memorization is painful. Just fight through it and do it anyway. Memorization is an important skill in learning things, so you should get over your fear of it.
Here’s how you memorize things:
• Tell yourself you will do it. Don’t try to find tricks or easy ways out of it, just sit down and do it.
• Write what you want to memorize on some index cards. Put one half of what you need to learn on one side, then another half on the other side.
• Every day for about 15 to 30 minutes, drill yourself on the index cards, trying to recall each one. Put any cards you don’t get right into a different pile, just drill those cards until you get bored, then try the whole deck and see if you improve.
• Before you go to bed, drill just the cards you got wrong for about 5 minutes, then go to sleep.
There are other techniques, like you can write what you need to learn on a sheet of paper, laminate it, then stick it to the wall of your shower. While you’re bathing, drill the knowledge without looking, and when you get stuck glance at it to refresh your memory.
If you do this every day, you should be able to memorize most things I tell you to memorize in about a week to a month. Once you do, nearly everything else becomes easier and intuitive, which is the purpose of memorization. It’s not to teach you abstract concepts but rather to ingrain the basics so that they are intuitive and you don’t have to think about them. Once you’ve memorized these basics they stop being speed bumps preventing you from learning more advanced abstract concepts.
The Setup
In this appendix you will be instructed to do three things:
• Do some things in your shell (command line, Terminal, PowerShell).
• Learn about what you just did.
• Do more on your own.
For this first exercise you’ll be expected to get your Terminal open and working so that you can do the rest of the appendix.
Do This
Get your Terminal, shell, or PowerShell working so you can access it quickly and know that it works.
macOS
For macOS you’ll need to do this:
• Hold down the command key and hit the spacebar.
• A search bar will pop up.
• Type: Terminal
• Click on the Terminal application that looks kind of like a black box.
• This will open Terminal.
• You can now go to your dock and CTRL-click to pull up the menu, then select Options → Keep In dock.
Now you have your Terminal open, and it’s in your dock so you can get to it.
Linux
I’m assuming that if you have Linux then you already know how to get at your Terminal. Look through the menu for your window manager for anything named “Shell” or “Terminal.”
Windows
On Windows we’re going to use PowerShell. People used to work with a program called cmd.exe, but it’s not nearly as usable as PowerShell. If you have Windows 7 or later, do this:
• Click Start.
• In “Search programs and files” type “powershell.”
• Hit Enter.
If you don’t have Windows 7, you should seriously consider upgrading. If you still insist on not upgrading, then you can try installing PowerShell from Microsoft’s download center. Search online to find “powershell downloads” for your version of Windows. You are on your own, though, since I don’t have Windows XP, but hopefully the PowerShell experience is the same.
You Learned This
You learned how to get your Terminal open so you can do the rest of this appendix.
Warning!
If you have that really smart friend who already knows Linux, ignore her when she tells you to use something other than Bash. I’m teaching you Bash. That’s it. She will claim that zsh will give you 30 more IQ points and win you millions in the stock market. Ignore her. Your goal is to get capable enough, and at this level it doesn’t matter which shell you use. The next warning is stay off IRC or other places where “hackers” hang out. They think it’s funny to hand you commands that can destroy your computer. The command rm -rf / is a classic that you must never type. Just avoid them. If you need help, make sure you get it from someone you trust and not from random idiots on the internet.
Do More
This exercise has a large “do more” part. The other exercises are not as involved as this one, but I’m having you prime your brain for the rest of the appendix by doing some memorization. Just trust me: this will make things silky smooth later on.
Linux/macOS
Take this list of commands and create index cards with the names on the left on one side, and the definitions on the other side. Drill them every day while continuing with the lessons in this appendix.
pwd print working directory
hostname my computer’s network name
mkdir make directory
cd change directory
ls list directory
rmdir remove directory
pushd push directory
popd pop directory
cp copy a file or directory
mv move a file or directory
cat print the whole file
xargs execute arguments
find find files
grep find things inside files
man read a manual page
apropos find which manual page is appropriate
env look at your environment
echo print some arguments
export export/set a new environment variable
exit exit the shell
sudo DANGER! become super user root DANGER!
Windows
If you’re using Windows then here’s your list of commands:
pwd print working directory
hostname my computer’s network name
mkdir make directory
cd change directory
ls list directory
rmdir remove directory
pushd push directory
popd pop directory
cp copy a file or directory
robocopy robust copy
mv move a file or directory
more page through a file
type print the whole file
forfiles run a command on lots of files
dir -r find files
select-string find things inside files
help read a manual page
helpctr find what manual page is appropriate
echo print some arguments
set export/set a new environment variable
exit exit the shell
runas DANGER! become super user root DANGER!
Drill, drill, drill! Drill until you can say these phrases right away when you see that word. Then drill the inverse, so that you read the phrase and know what command will do that. You’re building your vocabulary by doing this, but don’t spend so much time you go nuts and get bored.
Paths, Folders, Directories (pwd)
In this exercise you learn how to print your working directory with the pwd command.
Do This
I’m going to teach you how to read these “sessions” that I show you. You don’t have to type everything I list here, just some of the parts:
• You do not type in the $ (Unix) or < (Windows). That’s just me showing you my session so you can see what I got.
• You type in the stuff after $ or <, then hit Enter. So if I have $ pwd, you type just pwd and hit Enter.
• You can then see what I have for output followed by another $ or < prompt. That content is the output, and you should see the same output.
Let’s do a simple first command so you can get the hang of this:
Linux/macOS
Exercise 2 Session
$ pwd
/Users/zedshaw
$
PS C:Userszed> pwd
Path
----
C:Userszed
PS C:Userszed<
Warning!
In this appendix I need to save space so that you can focus on the important details of the commands. To do this, I’m going to strip out the first part of the prompt (the PS C:Userszed above) and leave just the little > part. This means your prompt won’t look exactly the same, but don’t worry about that. Remember that from now on I’ll only have the > to tell you that’s the prompt. I’m doing the same thing for the Unix prompts, but Unix prompts are so varied that most people get used to $ meaning “just the prompt.”
You Learned This
Your prompt will look different from mine. You may have your user name before the $ and the name of your computer. On Windows it will probably look different too. The key is that you see the following pattern:
• There’s a prompt.
• You type a command there. In this case, it’s pwd.
• It printed something.
• Repeat.
You just learned what pwd does, which means “print working directory.” What’s a directory? It’s a folder. Folder and directory are the same thing, and they’re used interchangeably. When you open your file browser on your computer to graphically find files, you are walking through folders. Those folders are the exact same things as these “directories” we’re going to work with.
Do More
• Type pwd 20 times and each time say “print working directory.”
• Write down the path that this command gives you. Find it with your graphical file browser of choice.
• No, seriously, type it 20 times and say it out loud. Sssh. Just do it.
If You Get Lost
As you go through these instructions you may get lost. You may not know where you are or where a file is and have no idea how to continue. To solve this problem I am going to teach you the commands to type to stop being lost.
Whenever you get lost, it is most likely because you were typing commands and have no idea where you’ve ended up. What you should do is type pwd to print your current directory. This tells you where you are.
The next thing is you need to have a way of getting back to where you are safe, your home. To do this type cd ~ and you are back in your home.
This means if you get lost at any time type:
pwd
cd ~
The first command pwd tells you where you are. The second command cd ~ takes you home so you can try again.
Do This
Right now figure out where you are, and then go home using pwd and cd ~. This will make sure you are always in the right place.
You Learned This
How to get back to your home if you ever get lost.
Make a Directory (mkdir)
In this exercise you learn how to make a new directory (folder) using the mkdir command.
Do This
Remember! You need to go home first! Do your pwd then cd ~ before doing this exercise. Before you do all exercises in this appendix, always go home first!
Exercise 4 Session
$ pwd
$ cd ~
$ mkdir temp
$ mkdir temp/stuff
$ mkdir temp/stuff/things
$ mkdir -p temp/stuff/things/orange/apple/pear/grape
$
Windows
Exercise 4 Windows Session
> pwd
> cd ~
> mkdir temp
Directory: C:Userszed
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:02 AM temp
> mkdir temp/stuff
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:02 AM stuff
> mkdir temp/stuff/things
Directory: C:Userszed empstuff
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM things
> mkdir temp/stuff/things/orange/apple/pear/grape
Directory: C:Userszed empstuff hingsorangeapplepear
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM grape
>
This is the only time I’ll list the pwd and cd ~ commands. They are expected in the exercises every time. Do them all the time.
You Learned This
Now we get into typing more than one command. These are all the different ways you can run mkdir. What does mkdir do? It makes directories. Why are you asking that? You should be doing your index cards and getting your commands memorized. If you don’t know that “mkdir makes directories” then keep working the index cards.
What does it mean to make a directory? You might call directories “folders.” They’re the same thing. All you did above is create directories inside directories inside of more directories. This is called a “path” and it’s a way of saying “first temp, then stuff, then things, and that’s where I want it.” It’s a set of directions to the computer of where you want to put something in the tree of folders (directories) that make up your computer’s hard disk.
Warning!
In this appendix I’m using the / (slash) character for all paths since they work the same on all computers now. However, Windows users will need to know that you can also use the (backslash) character and other Windows users will typically expect that at times.
Do More
• The concept of a “path” might confuse you at this point. Don’t worry. We’ll do a lot more with them, and then you’ll get it.
• Make 20 other directories inside the temp directory in various levels. Go look at them with a graphical file browser.
• Make a directory with a space in the name by putting quotes around it: mkdir "I Have Fun"
• If the temp directory already exists then you’ll get an error. Use cd to change to a work directory that you can control and try it there. On Windows, Desktop is a good place.
Change Directory (cd)
In this exercise you learn how to change from one directory to another using the cd command.
Do This
I’m going to give you the instructions for these sessions one more time:
• You do not type in the $ (Unix) or > (Windows).
• You type in the stuff after this, then hit Enter. If I have $ cd temp, you just type cd temp and hit Enter.
• The output comes after you hit Enter, followed by another $ or > prompt.
• Always go home first! Do pwd and then cd ~, so you go back to your starting point.
Linux/macOS
Exercise 5 Session
$ cd temp
$ pwd
~/temp
$ cd stuff
$ pwd
~/temp/stuff
$ cd things
$ pwd
~/temp/stuff/things
$ cd orange/
$ pwd
~/temp/stuff/things/orange
$ cd apple/
$ pwd
~/temp/stuff/things/orange/apple
$ cd pear/
$ pwd
~/temp/stuff/things/orange/apple/pear
$ cd grape/
$ pwd
~/temp/stuff/things/orange/apple/pear/grape
$ cd ..
$ cd ..
$ pwd
~/temp/stuff/things/orange/apple
$ cd ..
$ cd ..
$ pwd
~/temp/stuff/things
$ cd ../../..
$ pwd
~/
$ cd temp/stuff/things/orange/apple/pear/grape
$ pwd
~/temp/stuff/things/orange/apple/pear/grape
$ cd ../../../../../../../
$ pwd
~/
$
Windows
Exercise 5 Windows Session
> cd temp
> pwd
Path
----
C:Userszed emp
> cd stuff
> pwd
Path
----
C:Userszed empstuff
> cd things
> pwd
Path
----
C:Userszed empstuff hings
> cd orange
> pwd
Path
----
C:Userszed empstuff hingsorange
> cd apple
> pwd
Path
----
C:Userszed empstuff hingsorangeapple
> cd pear
> pwd
Path
----
C:Userszed empstuff hingsorangeapplepear
> cd grape
> pwd
Path
----
C:Userszed empstuff hingsorangeapplepeargrape
> cd ..
> cd ..
> cd ..
> pwd
Path
----
C:Userszed empstuff hingsorange
> cd ../..
> pwd
Path
----
C:Userszed empstuff
> cd ..
> cd ..
> cd temp/stuff/things/orange/apple/pear/grape
> cd ../../../../../../../
> pwd
Path
----
C:Userszed
>
You Learned This
You made all these directories in the last exercise, and now you’re just moving around inside them with the cd command. In my session above I also use pwd to check where I am, so remember not to type the output that pwd prints. For example, on line 3 you see ~/temp, but that’s the output of pwd from the prompt above it. Do not type this in.
You should also see how I use the .. to move “up” in the tree and path.
Do More
A very important part of learning to use the command line interface (CLI) on a computer with a graphical user interface (GUI) is figuring out how they work together. When I started using computers there was no GUI, and you did everything with the DOS prompt (the CLI). Later, when computers became powerful enough that everyone could have graphics, it was simple for me to match CLI directories with GUI windows and folders.
Most people today, however, have no comprehension of the CLI, paths, and directories. In fact, it’s very difficult to teach it to them, and the only way to learn about the connection is for you to constantly work with the CLI until one day it clicks that things you do in the GUI will show up in the CLI.
The way you do this is by spending some time finding directories with your GUI file browser, then going to them with your CLI. This is what you’ll do next.
• cd to the apple directory with one command.
• cd back to temp with one command, but not further above that.
• Find out how to cd to your “home directory” with one command.
• cd to your Documents directory, then find it with your GUI file browser (Finder, Windows Explorer, etc.).
• cd to your Downloads directory, then find it with your file browser.
• Find another directory with your file browser, then cd to it.
• Remember when you put quotes around a directory with spaces in it? You can do that with any command. For example, if you have a directory I Have Fun, then you can do: cd "I Have Fun".
List Directory (ls)
In this exercise you learn how to list the contents of a directory with the ls command.
Do This
Before you start, make sure you cd back to the directory above temp. If you have no idea where you are, use pwd to figure it out and then move there.
Linux/macOS
Exercise 6 Session
$ cd temp
$ ls
stuff
$ cd stuff
$ ls
things
$ cd things
$ ls
orange
$ cd orange
$ ls
apple
$ cd apple
$ ls
pear
$ cd pear
$ ls
$ cd grape
$ ls
$ cd ..
$ ls
grape
$ cd ../../../
$ ls
orange
$ cd ../../
$ ls
stuff
$
Windows
Exercise 6 Windows Session
> cd temp
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM stuff
> cd stuff
> ls
Directory: C:Userszed empstuff
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM things
> cd things
> ls
Directory: C:Userszed empstuff hings
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM orange
> cd orange
> ls
Directory: C:Userszed empstuff hingsorange
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM apple
> cd apple
> ls
Directory: C:Userszed empstuff hingsorangeapple
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM pear
> cd pear
> ls
Directory: C:Userszed empstuff hingsorangeapplepear
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM grape
> cd grape
> ls
> cd ..
> ls
Directory: C:Userszed empstuff hingsorangeapplepear
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM grape
> cd ..
> ls
Directory: C:Userszed empstuff hingsorangeapple
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM pear
> cd ../../..
> ls
Directory: C:Userszed empstuff
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM things
> cd ..
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM stuff
>
You Learned This
The ls command lists out the contents of the directory you are currently in. You can see me use cd to change into different directories and then list what’s in them so I know which directory to go to next.
There are a lot of options for the ls command, but you’ll learn how to get help on those later when we cover the help command.
Do More
• Type every one of these commands in! You have to actually type these to learn them. Just reading them is not good enough. I’ll stop yelling now.
• On Unix, try the ls -lR command while you’re in temp.
• On Windows do the same thing with dir -R.
• Use cd to get to other directories on your computer, and then use ls to see what’s in them.
• Update your notebook with new questions. I know you probably have some, because I’m not covering everything about this command.
• Remember that if you get lost, use ls and pwd to figure out where you are, and then go to where you need to be with cd.
Remove Directory (rmdir)
In this exercise you learn how to remove an empty directory.
Exercise 7 Session
$ cd temp
$ ls
stuff
$ cd stuff/things/orange/apple/pear/grape/
$ cd ..
$ rmdir grape
$ cd ..
$ rmdir pear
$ cd ..
$ ls
apple
$ rmdir apple
$ cd ..
$ ls
orange
$ rmdir orange
$ cd ..
$ ls
things
$ rmdir things
$ cd ..
$ ls
stuff
$ rmdir stuff
$ pwd
~/temp
$
Warning!
If you try to do rmdir on macOS and it refuses to remove the directory even though you are positive it’s empty, then there is actually a file in there called .DS_Store. In that case, type rm -rf <dir> instead (replace <dir> with the directory name).
Windows
Exercise 7 Windows Session
> cd temp
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:03 AM stuff
> cd stuff/things/orange/apple/pear/grape/
> cd ..
> rmdir grape
> cd ..
> rmdir pear
> cd ..
> rmdir apple
> cd ..
> rmdir orange
> cd ..
> ls
Directory: C:Userszed empstuff
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:14 AM things
> rmdir things
> cd ..
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/17/2011 9:14 AM stuff
> rmdir stuff
> pwd
Path
----
C:Userszed emp
> cd ..
>
You Learned This
I’m now mixing up the commands, so make sure you type them exactly and pay attention. Every time you make a mistake, it’s because you aren’t paying attention. If you find yourself making many mistakes, then take a break or just quit for the day. You’ve always got tomorrow to try again.
In this example you’ll learn how to remove a directory. It’s easy. You just go to the directory right above it, then type rmdir <dir>, replacing <dir> with the name of the directory to remove.
Do More
• Make 20 more directories and remove them all.
• Make a single path of directories that is 10 deep and remove them one at a time just like I did previously.
• If you try to remove a directory with contents, you will get an error. I’ll show you how to remove those in later exercises.
Moving Around (pushd, popd)
In this exercise you learn how to save your current location and go to a new location with pushd. You then learn how to return to the saved location with popd.
Do This
Linux/macOS
Exercise 8 Session
$ cd temp
$ mkdir i/like/icecream
$ pushd i/like/icecream
~/temp/i/like/icecream ~/temp
$ popd
~/temp
$ pwd
~/temp
$ pushd i/like
~/temp/i/like ~/temp
$ pwd
~/temp/i/like
$ pushd icecream
~/temp/i/like/icecream ~/temp/i/like ~/temp
$ pwd
~/temp/i/like/icecream
$ popd
~/temp/i/like ~/temp
$ pwd
~/temp/i/like
$ popd
~/temp
$ pushd i/like/icecream
~/temp/i/like/icecream ~/temp
$ pushd
~/temp ~/temp/i/like/icecream
$ pwd
~/temp
$ pushd
~/temp/i/like/icecream ~/temp
$ pwd
~/temp/i/like/icecream
$
Windows
Exercise 8 Windows Session
> cd temp
> mkdir i/like/icecream
Directory: C:Userszed empilike
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/20/2011 11:05 AM icecream
> pushd i/like/icecream
> popd
> pwd
Path
----
C:Userszed emp
> pushd i/like
> pwd
Path
----
C:Userszed empilike
> pushd icecream
> pwd
Path
----
C:Userszed empilikeicecream
> popd
> pwd
Path
----
C:Userszed empilike
> popd
>
Warning!
In Windows you normally don’t need the -p option like you do in Linux. However, I believe this is a more recent development, so you may run into older Windows PowerShell versions that do require the -p. If you have more information on this please email me at [email protected], so I can sort out whether to mention -p for Windows or not.
You Learned This
You’re getting into programmer territory with these commands, but they’re so handy I have to teach them to you. These commands let you temporarily go to a different directory and then come back, easily switching between the two.
The pushd command takes your current directory and “pushes” it into a list for later, then it changes to another directory. It’s like saying, “Save where I am, then go here.”
The popd command takes the last directory you pushed and “pops” it off, taking you back there.
Finally, on Unix pushd, if you run it by itself with no arguments, it will switch between your current directory and the last one you pushed. It’s an easy way to switch between two directories. This does not work in PowerShell.
Do More
• Use these commands to move around directories all over your computer.
• Remove the i/like/icecream directories and make your own, then move around in them.
• Explain to yourself the output that pushd and popd will print out for you. Notice how it works like a stack?
• You already know this, but remember that mkdir -p (on Linux/macOS) will make an entire path even if all the directories don’t exist. That’s what I did first for this exercise.
• Remember that Windows will make a full path and does not need the -p.
Making Empty Files (touch/New-Item)
In this exercise you learn how to make an empty file using the touch (New-Item on Windows) command.
Do This
Linux/macOS
Exercise 9 Session
$ cd temp
$ touch iamcool.txt
$ ls
iamcool.txt
$
Windows
Exercise 9 Windows Session
> cd temp
> New-Item iamcool.txt -type file
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/17/2011 9:03 AM iamcool.txt
>
You Learned This
You learned how to make an empty file. On Unix touch does this, and it also changes the times on the file. I rarely use it for anything other than making empty files. On Windows you don’t have this command, so you learned how to use the New-Item command, which does the same thing but can also make new directories.
Do More
• Unix: Make a directory, change to it, and then make a file in it. Then change one level up and run the rmdir command in this directory. You should get an error. Try to understand why you got this error.
• Windows: Do the same thing, but you won’t get an error. You’ll get a prompt asking if you really want to remove the directory.
Copy a File (cp)
In this exercise you learn how to copy a file from one location to another with the cp command.
Do This
Linux/macOS
Exercise 10 Session
$ cd temp
$ cp iamcool.txt neat.txt
$ ls
iamcool.txt neat.txt
$ cp neat.txt awesome.txt
$ ls
awesome.txt iamcool.txt neat.txt
$ cp awesome.txt thefourthfile.txt
$ ls
awesome.txt iamcool.txt neat.txt thefourthfile.txt
$ mkdir something
$ cp awesome.txt something/
$ ls
awesome.txt iamcool.txt neat.txt something thefourthfile.txt
$ ls something/
awesome.txt
$ cp -r something newplace
$ ls newplace/
awesome.txt
$
Windows
Exercise 10 Windows Session
> cd temp
> cp iamcool.txt neat.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
> cp neat.txt awesome.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 awesome.txt
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
> cp awesome.txt thefourthfile.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 awesome.txt
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
> mkdir something
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM something
> cp awesome.txt something/
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 awesome.txt
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
> ls something
Directory: C:Userszed empsomething
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 awesome.txt
> cp -recurse something newplace
> ls newplace
Directory: C:Userszed emp
ewplace
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 awesome.txt
>
You Learned This
Now you can copy files. It’s simple to just take a file and copy it to a new one. In this exercise I also make a new directory and copy a file into that directory.
I’m going to tell you a secret about programmers and system administrators now. They are lazy. I’m lazy. My friends are lazy. That’s why we use computers. We like to make computers do boring things for us. In the exercises so far you have been typing repetitive boring commands so that you can learn them, but usually it’s not like this. Usually, if you find yourself doing something boring and repetitive there’s probably a programmer who has figured out how to make it easier. You just don’t know about it yet.
The other thing about programmers is they aren’t nearly as clever as you think. If you overthink what to type, then you’ll probably get it wrong. Instead, try to imagine what the name of a command is to you and try it. Chances are that it’s a name or some abbreviation similar to what you thought it was. If you still can’t figure it out intuitively, then ask around and search online. Hopefully, it’s not something really stupid like ROBOCOPY.
Do More
• Use the cp -r command to copy more directories with files in them.
• Copy a file to your home directory or desktop.
• Find these files in your GUI and open them in a text editor.
• Notice how sometimes I put a / (slash) at the end of a directory? That makes sure the file is really a directory, so if the directory doesn’t exist I’ll get an error.
Moving a File (mv)
In this exercise you learn how to move a file from one location to another using the mv command.
Do This
Linux/macOS
Exercise 11 Session
$ cd temp
$ mv awesome.txt uncool.txt
$ ls
newplace uncool.txt
$ mv newplace oldplace
$ ls
oldplace uncool.txt
$ mv oldplace newplace
$ ls
newplace uncool.txt
$
Windows
Exercise 11 Windows Session
> cd temp
> mv awesome.txt uncool.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM newplace
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
-a--- 12/22/2011 4:49 PM 0 uncool.txt
> mv newplace oldplace
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM oldplace
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
-a--- 12/22/2011 4:49 PM 0 uncool.txt
> mv oldplace newplace
> ls newplace
Directory: C:Userszed emp
ewplace
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 12/22/2011 4:49 PM 0 awesome.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM newplace
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
-a--- 12/22/2011 4:49 PM 0 uncool.txt
>
You Learned This
Moving files or, rather, renaming them. It’s easy: give the old name and the new name.
Do More
Move a file in the newplace directory to another directory, then move it back.
View a File (less/more)
To do this exercise you’re going to do some work using the commands you know so far. You’ll also need a text editor that can make plain text (.txt) files. Here’s what you do:
• Open your text editor and type some stuff into a new file. On macOS this could be TextWrangler. On Windows this might be Notepad++. On Linux this could be gedit. Any editor will work.
• Save that file to your desktop and name it test.txt.
• In your shell use the commands you know to copy this file to your temp directory that you’ve been working with.
Once you’ve done that, complete this exercise.
Do This
Linux/macOS
Exercise 12 Session
$ less test.txt
[displays file here]
$
That’s it. To get out of less just type q (as in quit).
Windows
Exercise 12 Windows Session
> more test.txt
[displays file here]
>
Warning!
In the preceding output I’m showing [displays file here] to “abbreviate” what that program shows. I’ll do this when I mean to say, “Showing you the output of this program is too complex, so just insert what you see on your computer here and pretend I did show it to you.” Your screen will not actually show this.
You Learned This
This is one way to look at the contents of a file. It’s useful because if the file has many lines, it will “page” so that only one screenful at a time is visible. In the Do More section you’ll play with this some more.
Do More
• Open your text file again and repeatedly copy-paste the text so that it’s about 50–100 lines long.
• Copy it to your temp directory again so you can look at it.
• Now do the exercise again, but this time page through it. On Unix you use the spacebar and w (the letter w) to go down and up. Arrow keys also work. On Windows just hit the spacebar to page through.
• Look at some of the empty files you created, too.
• The cp command will overwrite files that already exist, so be careful copying files around.
Stream a File (cat)
You’re going to do some more setup for this one so you get used to making files in one program and then accessing them from the command line. With the same text editor from the last exercise, create another file named test2.txt, but this time save it directly to your temp directory.
$ less test2.txt
[displays file here]
$ cat test2.txt
I am a fun guy.
Don't you know why?
Because I make poems,
that make babies cry.
$ cat test.txt
Hi there this is cool.
$
Windows
Exercise 13 Windows Session
> more test2.txt
[displays file here]
> cat test2.txt
I am a fun guy.
Don't you know why?
Because I make poems,
that make babies cry.
> cat test.txt
Hi there this is cool.
>
Remember that when I say [displays file here] I’m abbreviating the output of that command so I don’t have to show you exactly everything.
You Learned This
Do you like my poem? Totally going to win a Nobel. Anyway, you already know the first command, and I’m just having you check that your file is there. Then you cat the file to the screen. This command just spews the whole file to the screen with no paging or stopping. To demonstrate that, I have you do this to test.txt, which should just spew a bunch of lines from that exercise.
Do More
• Make a few more text files and work with cat.
• Unix: Try cat test.txt test2.txt, and see what it does.
• Windows: Try cat test.txt,test2.txt, and see what it does.
Do This
Exercise 14 Session
$ cd temp
$ ls
uncool.txt iamcool.txt neat.txt something thefourthfile.txt
$ rm uncool.txt
$ ls
iamcool.txt neat.txt something thefourthfile.txt
$ rm iamcool.txt neat.txt thefourthfile.txt
$ ls
something
$ cp -r something newplace
$
$ rm something/awesome.txt
$ rmdir something
$ rm -rf newplace
$ ls
$
Windows
Exercise 14 Windows Session
> cd temp
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM newplace
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
-a--- 12/22/2011 4:49 PM 0 uncool.txt
> rm uncool.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM newplace
d---- 12/22/2011 4:52 PM something
-a--- 12/22/2011 4:49 PM 0 iamcool.txt
-a--- 12/22/2011 4:49 PM 0 neat.txt
-a--- 12/22/2011 4:49 PM 0 thefourthfile.txt
> rm iamcool.txt
> rm neat.txt
> rm thefourthfile.txt
> ls
Directory: C:Userszed emp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/22/2011 4:52 PM newplace
d---- 12/22/2011 4:52 PM something
> cp -r something newplace
> rm something/awesome.txt
> rmdir something
> rm -r newplace
> ls
>
You Learned This
Here we clean up the files from the last exercise. Remember when I had you try to rmdir on a directory with something in it? Well, that failed because you can’t remove a directory with files in it. To do that you have to remove the file or recursively delete all of its contents. That’s what you did at the end of this.
Do More
• Clean up everything in temp from all the exercises so far.
• Write in your notebook to be careful when running recursive remove on files.
$ exit
Windows
Exercise 23 Windows Session
> exit
You Learned This
Your final exercise is how to exit a Terminal. Again this is very easy, but I’m going to have you do more.
Do More
For your last set of exercises I’m going to have you use the help system to look up a set of commands you should research and learn how to use on your own.
Here’s the list for Unix:
• xargs
• sudo
• chmod
• chown
For Windows look up these things:
• forfiles
• runas
• attrib
• icacls
Find out what these are, play with them, and then add them to your index cards.
Command Line Next Steps
You have completed the crash course. At this point you should be a barely capable shell user. There’s a whole huge list of tricks and key sequences you don’t know yet, and I’m going to give you a few final places to go research more.
Unix Bash References
The shell you’ve been using is called Bash. It’s not the greatest shell, but it’s everywhere and has a lot of features, so it’s a good start. Here’s a short list of links about Bash you should go read:
Bash Cheat Sheet https://learncodethehardway.org/unix/bash_cheat_sheet.pdf (created by Raphael and CC licensed)
Reference Manual http://www.gnu.org/software/bash/manual/bashref.html
PowerShell References
On Windows there’s really only PowerShell. Here’s a list of useful links for you related to PowerShell:
Owner’s Manual http://technet.microsoft.com/en-us/library/ee221100.aspx
Master PowerShell http://powershell.com/cs/blogs/ebook/default.aspx