Learn Bash Scripting by Building Five Programs

Welcome to the Bash Scripting lessons!

10. Start the Terminal

10.1

The first thing you need to do is start the terminal. Do that by clicking the "hamburger" menu at the top left of the screen, going to the "terminal" section, and clicking "new terminal". Once you open a new one, type echo hello bash into the terminal and press enter.

HINTS

Capitalization matters
If the tests don't run automatically, "trash" all the terminals and try the instructions again

20. touch questionnaire.sh

20.1

You can run commands in the terminal or put them in a file to be run as a script. You will be making five small programs to learn some scripting. The first one will be a "questionnaire". Use the touch command to create questionnaire.sh in the project folder.

HINTS

Type touch questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

30. Add echo questionnaire

30.1

To start, open the file in the main editor by clicking the filename in the left side panel. Then, add the text echo hello questionnaire at the top of the file.

HINTS

If the left side panel isn't visible, click the icon that looks like two pieces of paper at the top left to open the panel. Then, click on your file to open it
Add the suggested text to the questionnaire.sh file

35. sh questionnaire.sh

35.1

Your script has one command. Run it with sh questionnaire.sh to see what happens. sh stands for shell.

HINTS

Type sh questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

40. bash questionnaire.sh

40.1

Using sh to run your script uses the shell interpreter. Run your script again with bash questionnaire.sh to use the bash interpreter. bash stands for bourne-again shell.

HINTS

Type bash questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

50. which bash

50.1

The output was the same. There are many interpreters which may not give the output you expect. Find out where the bash interpreter is located by entering which bash in the terminal.

HINTS

Type which bash in the terminal and press enter

60. Add shebang

60.1

That's the absolute path to the bash interpreter. You can tell your program to use it by placing a shebang at the very top of the file like this: #!<path_to_interpreter>. Add a shebang at the very top of your file, the one you want looks like this: #!/bin/bash.

HINTS

Add #!/bin/bash at the top of your questionnaire.sh file

70. ./questionnaire

70.1

Now, instead of using sh or bash to run your script. You can run it by executing the file and it will default to bash. Execute your script with ./questionnaire.sh. You will get a permission denied error.

HINTS

Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

80. ls -l

80.1

You should have got a permission denied message because you don't have permissions to execute the script. List what's in the project folder in long list format with ls -l to see the file permissions.

HINTS

Type ls -l in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

90. chmod +x questionnaire.sh

90.1

Next to your file is -rw-r--r--. All but the first character (-) describe permissions different users have with the file. r means read, w means write, x means execute. I don't see an x anywhere, so nobody can execute it. Enter chmod +x questionnaire.sh in the terminal to give everyone executable permissions.

HINTS

Type chmod +x questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

100. ls -l

100.1

List what's in the folder again with ls -l to see the new permissions.

HINTS

Type ls -l in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

110. ./questionnaire

110.1

The x was added by each type of user to denote that anyone can execute the file. Run your file again by executing it with ./questionnaire.sh.

HINTS

Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

140. Add ls -l

140.1

Now it works. In your script, you can add any commands that you would be able to enter in the terminal. Test this by adding the ls -l command below your other command.

HINTS

Add ls -l at the bottom of your questionnaire.sh file

150. ./questionnaire

150.1

Run the script by executing it again.

HINTS

Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

160. Delete all - shebang

160.1

Your script printed the result of the two commands as if you entered them in the terminal. Delete everything but the shebang from your file so you can start making the questionnaire.

HINTS

Only #!/bin/bash should remain in your questionnaire.sh file

170. Add QUESTION1 variable

170.1

Bash has variables, functions, and other things you might be familiar with. You can create a variable with VARIABLE_NAME=VALUE. There cannot be any spaces around the equal (=) sign. If a variable has any spaces in it, place double quotes around it. Create a variable named QUESTION1 and set it's value to "What's your name?".

HINTS

Add QUESTION1="What's your name?" at the bottom of your questionnaire.sh file

180. Add echo $QUESTION1

180.1

To use a variable, place $ in front of it like this: $VARIABLE_NAME. Shell scripts run from top to bottom, so you can only use variable below where it's created. Use echo to print your variable.

HINTS

Add echo $QUESTION1 at the bottom of your questionnaire.sh file

190. ./questionnaire

190.1

Run the file like you did before to see if it worked.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

200. Add read NAME

200.1

The question was printed. Next, you want to be able to accept input from a user. You can do that with read like this: read VARIABLE_NAME. This will get user input and store it into a new variable. After you print the question, use read to get input and store it in a variable named NAME.

HINTS

Add read NAME at the bottom of your questionnaire.sh file

210. Add echo Hello $NAME

210.1

At the bottom of your script, use echo to print Hello <name>. to the terminal.

HINTS

You can use your NAME variable like this: $NAME
Use your $NAME variable in place of <name>
Don't forget the period
Add echo Hello $NAME. at the bottom of your script

220. ./questionnaire

220.1

Run the file again. Type your name and press enter after it asks for it.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there
You can press ctrl+c to close the program

230. Add QUESTION2 variable

230.1

Right below your first variable, create another one named QUESTION2. Set the value to, Where are you from?. Make sure to put it in double quotes.

HINTS

Here's an example: VARIABLE="value"
Add QUESTION2="Where are you from?" to your script

240. Add echo $QUESTION2

240.1

After your read command, use your new variable to print the next question.

HINTS

Use echo to print the variable
Add echo $QUESTION2 below your read command

250. Add read LOCATION

250.1

Below where the second question is printed, use read to get input from the user into a variable named LOCATION.

HINTS

Here's an example read VARIABLE_NAME
Add read LOCATION to your script below echo $QUESTION2

260. Add echo Hello $NAME from $LOCATION

260.1

Change the existing response to Hello <name> from <location>..

HINTS

Use your two variables in place of <name> and <location
Use your two variables with $NAME and $LOCATION
Make sure the command is at the bottom of the file
The suggested command should look like: echo Hello $NAME from $LOCATION.

270. ./questionnaire

270.1

Run the script and enter values when it is waiting for input.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
You can press ctrl+c to close a program

280. Add echo " Questionnaire "

280.1

It's looking good. I want a title to appear when the program first starts. Use echo to print ~~ Questionnaire ~~ before anything else is printed.

HINTS

Add echo ~~ Questionnaire ~~ below your shebang

290. ./questionnaire

290.1

Run the script and enter values until it is done again so you can see what the title looks like.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
You can press ctrl+c to close the program

300. echo --help

300.1

It would be nice if there was some empty lines around the title. You've probably used the --help flag before, see if you can use it with echo to try and find a way to add empty lines.

HINTS

Enter the suggested command in the terminal
Here's an example: <command> <flag>
The command is echo, the flag is --help
Type echo --help in the terminal and press enter

310. man echo

310.1

That didn't work as I hoped. Another way to find information about a command is with man. It stands for manual and you can use it like this: man <command>. See if there's a manual for echo.

HINTS

Type man echo in the terminal and press enter
Press enter until you have seen the whole menu

320. Add echo -e \n Questionnaire \n

320.1

At the top of the menu, the -e option looks promising. And the \n below it says new line. You should take a look at those. In your script, change the title to echo -e \n~~ Questionnaire ~~\n to see if that prints the empty lines.

HINTS

Change the suggested line to echo -e \n~~ Questionnaire ~~\n

323. ./questionnaire

323.1

Run it to see if it worked. You can press ctrl+c to close the program after it starts if you don't want to enter values.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
You can press ctrl+c to close the program

326. Change to echo -e "\n Questionnaire \n"

326.1

It didn't print the empty lines. echo will only print empty lines if the value is enclosed in quotes. Place double quotes around the title that gets printed to see if it works.

HINTS

Change the suggested line to echo -e "\n~~ Questionnaire ~~\n"

330. ./questionnaire

330.1

Run your script again to see if that fixed it.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first
You can press ctrl+c to close the program

340. Add QUESTION3 variable

340.1

Now it's working 😄 Create a QUESTION3 variable next to the other two, set it's value to "What's your favorite coding website?"

HINTS

Add QUESTION3="What's your favorite coding website?" to your questionnaire.sh file
Add it by the other two variables

345. echo QUESTION3 variable

345.1

Use echo to print the third question after you read the LOCATION.

HINTS

Add echo $QUESTION3 below the read LOCATION
Add it to your questionnaire.sh file

350. read WEBSITE

350.1

After the question you just printed, add code to read input into a variable named WEBSITE.

HINTS

Add read WEBSITE below the echo $QUESTION3

360. echo final sentence

360.1

Change the echo command of the response to print this sentence instead: Hello <name> from <location>. I learned that your favorite coding website is <website>!.

HINTS

Replace the echo Hello $NAME from $LOCATION. with the suggested sentence
Use your three variables in place of <name>, <location>, and <website>
The command should look like this: echo Hello $NAME from $LOCATION. I learned that your favorite coding website is $WEBSITE!

363. ./questionnaire

363.1

Run the script and enter values when the program is waiting. Let's see the final output.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first

366. Add line breaks around final sentence

366.1

One last thing. Change that final response to print an empty line at the beginning of the sentence.

HINTS

Use echo with the -e flag and a new line (\n) character like you did for the title
Don't forget to put the response in double quotes so it prints the empty line
Here's an example: echo -e "\n<message>"
Only add a new line at the beginning of the response, not the end
The final command should look like this: echo "\nHello $NAME from $LOCATION. I learned that your favorite coding website is $WEBSITE!"

370. ./questionnaire

370.1

Run it one last time and enter values when it asks to see if you like how it looks.

HINTS

Run your file by executing it
Type ./questionnaire.sh in the terminal and press enter
Make sure you are in the project folder first

380. touch countdown.sh

380.1

It looks good. I think you are done with that script for now. The next program will be countdown timer. Use the touch command to create a new file named countdown.sh in your project folder.

HINTS

Type touch countdown.sh in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

390. chmod +x countdown.sh

390.1

Give your file executable permissions so you can run it like the other one. It's the chmod command with the +x flag.

HINTS

Here's an example chmod <permissions> <filename>
The value for permissions you want to use is +x
You previously used chmod +x questionnaire.sh
Type chmod +x countdown.sh in the terminal and press enter
Make sure you are in the project folder first

400. Add shebang

400.1

You want to use the bash interpreter again. Add a shebang at the top of your new file to denote that.

HINTS

A shebang looks like this: #!<path_to_interpreter>
Enter which bash in the terminal to see the path to bash
Look at the shebang in your first script to get the syntax
It should look like this: #!/bin/bash
Add #!/bin/bash at the top of your countdown.sh file

410. Add comment

410.1

Comments in bash look like this: # <comment>. Add a comment below the shebang that says Program that counts down to zero from a given argument so people know what it does. Note that the shebang is a special case and is not treated like a comment.

HINTS

Add # Program that counts down to zero from a given argument to your countdown.sh file

420. Add echo $*

420.1

Programs can take arguments. You can access them a few different ways with $. Add echo $* in your script to print all arguments passed to it.

HINTS

Add echo $* at the bottom of the countdown.sh file

425. ./countdown.sh

425.1

Execute your script with ./countdown.sh.

HINTS

Type ./countdown.sh in the terminal and press enter
Make sure you are in the project folder first

430. ./countdown.sh arg1 arg2 arg3

430.1

Nothing was printed. Run your script again, but this time add three arguments to the command; arg1, arg2, and arg3. Place them after the command with a space before each one.

HINTS

Type ./countdown.sh arg1 arg2 arg3 in the terminal and press enter
Make sure you are in the project folder first

440. Change to echo $1

440.1

$* printed all the arguments passed to your script. To access any one of them, use $<number>. arg2 could have been accessed with $2. Change your script to echo the first argument instead of all the arguments.

HINTS

Try running your script with an argument to make sure it’s giving the expected output
Use echo $1 to print the second argument
Change echo $* to echo $1 in your countdown.sh file

450. ./countdown.sh arg1 arg2 arg3

450.1

Run your file with ./countdown.sh arg1 arg2 arg3 again.

HINTS

Type ./countdown.sh arg1 arg2 arg3 in the terminal and press enter
Make sure you are in the project folder first

460. help

460.1

Now it just prints the first argument. Your program will accept an argument to count down from. You will test it with an if statement to make sure it's a positive integer. I wonder what that syntax would look like. Type help in the terminal to see if you can find anything.

HINTS

Type help in the terminal and press enter

470. man if

470.1

This is a list of built-in commands. You should look over it, some of them may look familiar. I see echo in there. Another one is if. See if you can find out more about it by checking its man page.

HINTS

Here's an example: man <command>
Type man if in the terminal and press enter

480. help if

480.1

I guess there isn't a man page for it. At the top of the help screen, I noticed you can use help <command> to find out more. Yet another way to find out about a command 😥 See if you can find out more about if with that method.

HINTS

Here's an example help <command>
Type help if in the terminal and press enter

490. Add if arg1 print true

490.1

The syntax is at the top, not all of it is required. Here's another example:

if [[ CONDITION ]]
then
  STATEMENTS
fi

Remove the echo $1 in your script and add an if condition that checks if [[ $1 == arg1 ]]. In its then area, use echo to print true to the screen. There must be spaces on the inside of the brackets ([[ ... ]]) and around the operator (==).

HINTS

Make sure to remove the echo $1
Add the following to your countdown.sh file:

if [[ $1 == arg1 ]]
then
  echo true
fi

500. ./countdown arg1

500.1

Notice that the end of the syntax is fi (if backwards). It should print true if you pass arg1 to your script now. Run the script with arg1 as the only argument.

HINTS

Type ./countdown.sh arg1 in the terminal and press enter
Make sure you are in the project folder first

505. ./countdown !arg1

505.1

The if condition worked, it printed true. Run it again with anything except arg1 as the first argument.

HINTS

Type ./countdown.sh arg2 in the terminal and press enter
Make sure you are in the project folder first

510. Add else print false

510.1

Nothing was printed. One of the optional parts of if was an else area. You can use it like this:

if [[ CONDITION ]]
then
  STATEMENTS
else
  STATEMENTS
fi

Add an else to your existing if condition. Use echo to print false if the condition fails.

HINTS

Your if should look like this:

if [[ $1 == arg1 ]]
then
  echo true
else
  echo false
fi

520. ./countdown !arg1

520.1

Run the script again and use anything except arg1 as the only argument.

HINTS

Type ./countdown.sh !arg1 in the terminal and press enter
Make sure you are in the project folder first
Enter cd ~/project in the terminal to get to the project folder if you aren't there

530. Change if condition -lt 5

530.1

Now it printed false. Your program is expecting an integer to count down from as its argument. You can compare integers inside the brackets ([[ ... ]]) of your if with -eq (equal), -ne (not equal), -lt (less than), -le (less than or equal), -gt (greater than), -ge (greater than or equal). Change your if condition to check if your first argument is less than 5.

HINTS

Make sure there's spaces inside the brackets ([[ ... ]]) and around the operator (-lt)
Your if condition should look like this: [[ $1 -lt 5 ]]
The whole if should look like this:

if [[ $1 -lt 5 ]]
then
  echo true
else
  echo false
fi

540. ./countdown 4

540.1

Run the script again and use 4 as a first argument to make sure it's working.

HINTS

Type ./countdown.sh 4 in the terminal and press enter
Make sure you are in the project folder first

542. ./countdown 5

542.1

It printed true since your argument was less than 5. Run it again with 5 as the argument.

HINTS

Type ./countdown.sh 5 in the terminal and press enter
Make sure you are in the project folder first

544. help

544.1

As expected, that printed false. Take a look at that help menu again. I want to see if we can find out more about how these expressions work.

HINTS

Type help in the terminal and press enter

546. help [[ expression ]]

546.1

Near the top left, it says [[ expression ]]. Those look like the double brackets you are using. See if you can get more info about that with the help command like you did with help if.

HINTS

Here's an example: help <command>
Type help [[ expression ]] or help [[ in the terminal and press enter

548. help test

548.1

It might not be a bad idea to read that. Looks like you can use some, probably familiar, things like !, &&, and || to compare multiple expressions. There's also == and != operators for an individual expression. It says something about the test built-in command. See if you can bring up the help menu for that.

HINTS

View the help menu of the suggested command like you did for the help if
Here's an example: help <command>
Type help test in the terminal and press enter

550. Change if to [[ $1 -le 5 ]]

550.1

That's what I was looking for. At the top are some file operators. There's some string and other operators as well. You should take a look at them. Near the bottom, are the arithmetic operators you used with your if condition. Change the condition in your script to check if the first argument is less than or equal to 5.

HINTS

The if condition should look like this: [[ $1 -le 5 ]]
Make sure there's spaces inside the brackets ([[ ... ]]) and around the operator (-le)
It's the if in your countdown.sh file

552. ./countdown 5

552.1

Run the script and use 5 as a first argument again.

HINTS

Type ./countdown.sh 5 in the terminal and press enter
Make sure you are in the project folder first

554. [[ 4 -le 5 ]]

554.1

Now it prints true. Remember I said any command can run in the terminal or a script. Try running an expression right in the terminal by entering [[ 4 -le 5 ]] in it.

HINTS

Enter the suggested expression in the terminal
Make sure there's spaces inside the brackets ([[ ... ]]) and around the operator (-le)
Type [[ 4 -le 5 ]] in the terminal and press enter

556. echo $?

556.1

Nothing happened? Each command has an exit status that can be accessed with $?. View the exit status of the last command with echo $?.

HINTS

Type echo $? in the terminal and press enter
Your second to last command should be [[ 4 -le 5 ]]. So enter that before echo $?

558. [[ 4 -ge 5 ]]

558.1

The exit status of 0 means it was true, 4 is indeed less or equal to 5. Try it again with [[ 4 -ge 5 ]].

HINTS

Enter the suggested expression in the terminal
Make sure there's spaces inside the brackets ([[ ... ]]) and around the operator (-ge)
Type [[ 4 -ge 5 ]] in the terminal and press enter

560. echo $?

560.1

Use echo to view the exit status of the command you just entered.

HINTS

Type echo $? in the terminal and press enter
Your second to last command should be [[ 4 -ge 5 ]]. So enter that right before echo $?

562. [[ 4 -ge 5 ]]; echo $?

562.1

It printed 1 this time for false. You can separate commands on a single line with ;. Enter your last two commands on one line like this: [[ 4 -ge 5 ]]; echo $?. It will run the expression, then print the exit status of it since it was the last command.

HINTS

Make sure there's spaces inside the brackets ([[ ... ]]) and around the operator (-ge)
Type [[ 4 -ge 5 ]]; echo $? in the terminal and press enter

564. [[ 10 -ne 5 ]]; echo $?

564.1

It's still false. Using the same syntax of [[ ... ]]; echo $?, check if 10 is not equal to 5 and print the exit status of the expression on one line.

HINTS

Check the help test menu to find the not equal operator
It's the -ne operator
You previously used [[ 4 -ge 5 ]]; echo $?
Make sure there's spaces inside the brackets and around the operator
Type [[ 10 -ne 5 ]]; echo $? in the terminal and press enter

566. bad_command; echo $?

566.1

You can think of an exit status of 0 as true. But it means that the command had zero errors. All commands have an exit status. Using the same syntax, enter bad_command; and check its exit status on a single line.

HINTS

The syntax looks like this: <command>; echo $?
You previously used [[ 10 -ne 5 ]]; echo $?
Type bad_command; echo $? in the terminal and press enter

568. ls; echo $?

568.1

command not found, with an exit status of 127. Anything but 0 means there was an error with the command. bad_command didn't exist. Try it again with ls.

HINTS

Use the same syntax you have been using
Here's an example <command>; echo $?
You previously used bad_command; echo $?
Type ls; echo $? in the terminal and press enter

570. ls -y; echo $?

570.1

The command executed as expected and there were zero errors. So it gave you an exit status of 0. Try it again with ls -y.

HINTS

Use the same syntax you have been using
Here's an example: <command>; echo $?
You previously used ls; echo $?
Type ls -y; echo $? in the terminal and press enter

572. help test

572.1

The -y flag doesn't work with ls so it gave you an exit status other than 0, meaning that the command was unsuccessful. View the help menu of the test command again, I want to see what else is in that list.

HINTS

Here's an example: help <command>
Type help test in the terminal and press enter

574. [[ -a countdown.sh ]]; echo $?

574.1

You tried a few of the arithmetic operators, those work for integers. Try one of the file operators. The first one on the list checks if a file exists. Type [[ -a countdown.sh ]]; echo $? in the terminal to see if your file exists.

HINTS

Enter the suggested commands in the terminal
Type [[ -a countdown.sh ]]; echo $? in the terminal and press enter
Don't forget the spaces inside the brackets
Make sure you are in the project folder first

575. [[ -a bad_file.txt ]]; echo $?

575.1

The file must exist. It's checking the folder the command is entered from. Try it again with bad_file.txt.

HINTS

Use the same syntax you have been using
Here's an example: <command>; echo $?
You previously used [[ -a countdown.sh ]]; echo $?
Type [[ -a bad_file.txt ]]; echo $? in the terminal and press enter
Don't forget the spaces inside the brackets

576. [[ -x countdown.sh ]]; echo $?

576.1

bad_file.txt doesn't exist. I think you're getting the hang of this. Using the same syntax, check if you have permissions to execute your countdown.sh file. You may want to look at that menu again.

HINTS

View the help test menu to find the file operator for checking if a file is executable by you
It's the -x operator
The syntax you want is [[ ... ]]; echo $? to see if the condition is true
Don't forget the spaces inside the brackets
Type [[ -x countdown.sh ]]; echo $? in the terminal and press enter
Make sure you are in the project folder first

582. help [[ expression ]]

582.1

You played around with a number of the expressions. View the help [[ expression ]] menu again that you looked at before to see a few more options. You can view the menu with just help [[.

HINTS

Enter the suggested command in the terminal
Type help [[ expression ]] or help [[ in the terminal and press enter

584. [[ -x countdown.sh && 5 -le 4 ]]; echo $?

584.1

As I mentioned before, you can test multiple expressions with && and ||. Enter [[ -x countdown.sh && 5 -le 4 ]]; echo $? in the terminal to test the file is executable by you and five is less than or equal to four.

HINTS

Enter the suggested command in the terminal
Type [[ -x countdown.sh && 5 -le 4 ]]; echo $? in the terminal and press enter
Make sure there's spaces around the brackets and all the operators

586. [[ -x countdown.sh || 5 -le 4 ]]; echo $?

586.1

Both conditions weren't true, so the exit status was 1 for false. Try testing the same two conditions with the or operator.

HINTS

Modify this [[ -x countdown.sh && 5 -le 4 ]]; echo $? with the suggestion and enter it in the terminal
Use the or operator from the help [[ expression ]] menu
The or operator is ||
Type [[ -x countdown.sh || 5 -le 4 ]]; echo $? in the terminal and press enter
Make sure there's spaces around the brackets and all the operators

588. Change if to [[ $1 -gt 0 ]]

588.1

One of the conditions was true so it printed 0. I think that's enough of a detour. Back in your script, change the if condition to check if the first argument is greater than zero so you can be sure it's something you can count down from.

HINTS

Use the -gt operator in your if condition
The if condition should look like this: [[ $1 -gt 0 ]]
It's in the countdown.sh file

590. Change if !# message

590.1

The condition you added checks if a positive integer was passed as an argument to the script and executes the then area. Change the existing echo command to print Include a positive integer as the first argument. if a positive integer is not used.

HINTS

The else area should look like this: echo Include a positive integer as the first argument.
The whole if condition should look like this:

if [[ $1 -gt 0 ]]
then
  echo true
else
  echo Include a positive integer as the first argument.
fi

600. ./countdown 1

600.1

Run your script and use 1 as a first argument to make sure the condition is working.

HINTS

Type ./countdown.sh 1 in the terminal and press enter
Make sure you are in the project folder first

610. ./countdown 0

610.1

Run it again and use anything but a positive integer as the only argument.

HINTS

Type ./countdown.sh 0 in the terminal and press enter
Make sure you are in the project folder first

615. help

615.1

Looks like your if condition is working. Next, you want to loop over the argument and count down to zero from it. Check the help menu to see if there's any commands for this.

HINTS

Enter the suggested command in the terminal
Type help in the terminal and press enter

620. Add for loop for countdown

620.1

There's two for loops in there, you want the second one. Here's an example:

for (( i = 10; i > 0; i-- ))
do
  echo $i
done

The above creates a variable (i = 10), then prints it, subtracts one, and repeats until i is not greater than 0. So it prints 10 through 1. In the then area of your condition, replace the echo with a for loop that prints from the argument ($1) to 1.

HINTS

Set the variable to the value of your argument ($1) initially
Use the same syntax as the example except change the 10 to $1
Don't include any extra commands in the then area
Your then area should look like this:

for (( i = $1; i > 0; i-- ))
do
  echo $i
done

The whole if condition should look like this:

if [[ $1 -gt 0 ]]
then
  for (( i = $1; i > 0; i-- ))
  do
    echo $i
  done
else
  echo Include a positive integer as the first argument.
fi

630. ./countdown 10

630.1

Run your script and use 10 as the first argument.

HINTS

Type ./countdown.sh 10 in the terminal and press enter
Make sure you are in the project folder first

640. help

640.1

It works 😄 But I want it to pause for one second between each number. Check the help menu again to see if there's any commands that might help.

HINTS

Enter the suggested command in the terminal
Type help in the terminal and press enter

650. ls /

650.1

I'm not seeing the command I was hoping to. These are the built-in commands, where are the rest? Type ls / to look around.

HINTS

Enter the suggested command in the terminal
Type ls / in the terminal and press enter

660. ls /bin

660.1

The / listed what's in the root of the file system. I see a bin folder, bin stands for binary. View what's in it with ls /bin.

HINTS

Enter the suggested command in the terminal
Type ls /bin in the terminal and press enter

670. man sleep

670.1

These are some non built-in commands. There's quite a few that should look familiar. One is bash, that's the one you used for the shebang in your scripts. I see one called sleep. View the manual of it.

HINTS

View a manual with the man command
Here's an example: man <command>
Enter man sleep in the terminal
Press enter until you have seen the whole menu

675. sleep 3

675.1

At the top, it says you can pause execution for a number of seconds. Try it out by entering sleep 3 in the terminal.

HINTS

Enter the suggested command in the terminal
Enter sleep 3 in the terminal

680. Add sleep to for loop

680.1

That should work. In your for loop, use sleep to make the script pause for 1 second after each number is printed.

HINTS

Add the suggestion to the for loop in your countdown.sh file
Add sleep 1 after you print i in your for loop

690. ./countdown 3

690.1

Run your script and use 3 as the first argument.

HINTS

Type ./countdown.sh 3 in the terminal and press enter
Make sure you are in the project folder first

692. Change to >=

692.1

Awesome. Except it should print 0 instead of stopping at 1. Change the condition in your for loop so that it checks for i >= 0.

HINTS

Your for loop should look like this:

for (( i = $1; i >= 0; i-- ))
do
  echo $i
  sleep 1
done

The whole if condition should look like this:

if [[ $1 -gt 0 ]]
then
  for (( i = $1; i >= 0; i-- ))
  do
    echo $i
    sleep 1
  done
else
  echo Include a positive integer as the first argument.
fi

694. ./countdown 3

694.1

Run your script with 3 as the argument again.

HINTS

Type ./countdown.sh 3 in the terminal and press enter
Make sure you are in the project folder first

696. Add echo -e "title"

696.1

Excellent. I want it to display a title like the other script. Make it so that it prints ~~ Countdown Timer ~~ before anything else. Include a new line before and after it like you did for the other title.

HINTS

Use the echo command with the -e flag and the new line (\n) character
Make sure to place the message in double quotes
Here's an example: echo -e "\n<message>\n"
Add echo -e "\n~~ Countdown Timer ~~\n" to the countdown.sh file after the comment

698. ./countdown 1

698.1

Run your script and use 1 as the first argument again to see the title.

HINTS

Type ./countdown.sh 1 in the terminal and press enter
Make sure you are in the project folder first

700. Add Multiline comment

700.1

This is fun. You can create a multiline comment like this:

: '
  comment here
  more comment here
'

Comment out your for loop with a multiline comment. I want to try and do this with a while loop.

HINTS

Comment out the for loop in your countdown.sh file with a multiline comment
Make sure there's a space between the : and '
Your for loop should look like this:

: '
for (( i = $1; i >= 0; i-- ))
do
  echo $i
  sleep 1
done
'

710. help while

710.1

View the help menu for the while command to see if you can find anything.

HINTS

Here's an example: help <command>
Enter help while in the terminal

730. Add I variable

730.1

It shows the syntax. First, below your comment, create a variable named I that is set to the value of your first argument. It will start there, then on each iteration of the while loop you can subtract 1 from it until it reaches 0.

HINTS

Add I=$1 in the then area of your if statements below the multi-line comment
The then area should look like this:

: '
for (( i = $1; i >= 0; i-- ))
do
  echo $i
  sleep 1
done
'
I=$1

740. Add while loop

740.1

The menu showed that you can make a while loop like this:

while [[ CONDITION ]]
do
  STATEMENTS
done

Add a while loop below the I variable you made. The condition should be $I -ge 0 and you should echo the I variable in the do statements.

HINTS

Your while loop should look like this:

while [[ $I -ge 0 ]]
do
  echo $I
done

750. Add (( I-- ))

750.1

I never changes here, so you would have an infinite loop. You can subtract one from I with double parenthesis (((...))) and the -- operator. In your while loop, add (( I-- )) after you echo $I to subtract one from I on each pass.

HINTS

Your while loop should look like this:

while [[ $I -ge 0 ]]
do
  echo $I
  (( I-- ))
done

760. Add sleep 1

760.1

The last thing to do is to add the sleep again. In your while loop, add the code to make it sleep for 1 second. Add the code after the (( I-- )).

HINTS

Use the same sleep 1 you used in the for loop
Your while loop should look like this:

while [[ $I -ge 0 ]]
do
  echo $I
  (( I-- ))
  sleep 1
done

770. ./countdown.sh 5

770.1

Run the script and use 5 as the first argument.

HINTS

Type ./countdown.sh 5 in the terminal and press enter
Make sure you are in the project folder first

780. touch bingo.sh

780.1

I think the countdown timer is finished. Feel free to try it with some other arguments. The next one is a bingo number generator. Use touch to create bingo.sh in the same folder as the others.

HINTS

Type touch bingo.sh in the terminal and press enter
Make sure you are in the project folder first

790. chmod +x bingo.sh

790.1

Give your file executable permissions like you did for the other two.

HINTS

Use the chmod command with the +x flag
Here's an example chmod <permissions> <filename>
You previously used chmod +x countdown.sh
Type chmod +x bingo.sh in the terminal and press enter

800. Add shebang

800.1

Add a shebang at the top of your new script. It should use bash again like other two.

HINTS

A shebang looks like this: #!<path_to_interpreter>
Enter which bash in the terminal to see the path to bash
Look at the shebang in one of your other scripts to get the syntax
It should look like this: #!/bin/bash
Add #!/bin/bash at the top of your bingo.sh file

810. Add comment

810.1

Add a comment below the shebang that says, Bingo Number Generator.

HINTS

Comments look like this: # <comment>
Add #Bingo Number Generator below the shebang
Capitalization matters

815. Add echo -e "title"

815.1

Before I forget, use a single echo command to print a title for this program. It should say ~~ Bingo Number Generator ~~ with an empty line before and after it.

HINTS

Use the echo command with the -e flag and the new line (\n) character
Don't forget the double quotes when using a new line character
Take a look at one of the title's from a previous file for a hint
Here's an example: echo -e "\n<message>\n"
You previously used echo -e "\n~~ Countdown Timer ~~\n"
Add echo -e "\n~~ Bingo Number Generator ~~\n" below the comment of your bingo.sh file

817. Add NUMBER=5 variable

817.1

In your script, create a NUMBER variable that equals 5.

HINTS

Here's an example: VARIABLE_NAME=VALUE
Add NUMBER=5 to the bottom of your bingo.sh file

818. echo $NUMBER

818.1

Below your new variable, use echo to print it to the screen.

HINTS

Here's an example: echo $<variable>
Use NUMBER in place of <variable>
Add echo $NUMBER at the bottom of your bingo.sh file

819. ./bingo.sh

819.1

Run the script by executing it.

HINTS

Type ./bingo.sh in the terminal and press enter
Make sure you are in the project folder first

820. printenv

820.1

The numbers in bingo go up to 75, each number has a letter from the word bingo associated with it. You will need to randomly generate a number between 1 and 75. Bash may have something that can help you here. A shell comes with environment variables. View them by entering printenv in the terminal.

HINTS

Type printenv in the terminal and press enter

822. echo $LANG

822.1

These are all environment variables, they are predefined and loaded with each shell. Most of them aren’t very relevant, but it’s nice to know they’re there. One of them is LANG. Use echo to print it in the terminal.

HINTS

Here's an example: echo $<variable>
Type echo $LANG in the terminal and press enter

824. declare -p

824.1

View all variables in the shell with declare -p. -p stands for print

HINTS

Type declare -p in the terminal and press enter

826. echo $RANDOM

826.1

This list includes all the environment variables, and any others that may have been created in the current shell. There's one named RANDOM. Use echo to print it in the terminal.

HINTS

Here's an example: echo $<variable>
Type echo $RANDOM in the terminal and press enter

828. Change to NUMBER=$RANDOM

828.1

Back in your script, use the RANDOM variable to set NUMBER to a random number instead of 5.

HINTS

Change NUMBER=5 to NUMBER=$RANDOM

830. ./bingo.sh

830.1

Run the script a few times in a row to make sure it's working.

HINTS

Type ./bingo.sh in the terminal and press enter two times in a row
Make sure you are in the project folder first

835. Change to NUMBER=$RANDOM%75

835.1

The RANDOM variable will generate a random number between 0 and 32767. You can use the modulus operator to make it in the range you want. In your script, change the NUMBER variable to $RANDOM%75.

HINTS

Change NUMBER=$RANDOM to NUMBER=$RANDOM%75

840. ./bingo.sh

840.1

Run the script again.

HINTS

Type ./bingo.sh in the terminal and press enter
Make sure you are in the project folder first

881. I=0

881.1

Bash sees everything as a string so it just printed the %75 part literally. In the terminal, create an I variable equal to 0 (zero), so you can play with it and figure out how to do some calculations.

HINTS

Type I=0 in the terminal and press enter

884. echo $I

884.1

In the terminal, use echo to print your new variable.

HINTS

Here's an example: echo $<variable>
Type echo $I in the terminal and press enter

887. (( I++ ))

887.1

I noticed that you used double parenthesis in the while loop of your countdown timer to subtract one from I. Type (( I++ )) in the terminal to see if anything happens.

HINTS

Type (( I++ )) in the terminal and press enter

890. echo $I

890.1

There was no output. Use echo to print I in the terminal again.

HINTS

Type echo $I in the terminal and press enter

891. help let

891.1

The double parenthesis performed the calculation, changing the value of I from 0 to 1. Enter help let in the terminal to see the operators you can use with the double parenthesis.

HINTS

Type help let in the terminal and press enter

893. (( I += 10 ))

893.1

You used several of these now, including in the for loop from the countdown timer. Enter (( I += 10 )) in the terminal to increment I by 10. Note that you don't need to prepend variables with $ inside these parenthesis.

HINTS

Type (( I += 10 )) in the terminal and press enter

896. echo $I

896.1

Use echo to print your I variable again.

HINTS

Type echo $I in the terminal and press enter.

897. $(( I + 4 ))

897.1

It should have printed 11 for the value of I. Using the double parenthesis like you have been is good for changing variable values or making comparisons. It makes the calculation in place and provides no output. If you want to make a calculation and do something with the result, add a $ in front like this: $(( ... )). Type $(( I + 4 )) in the terminal to see what happens.

HINTS

If it didn't print 11 for I, enter I=11 to set it to 11
Type $(( I + 4 )) in the terminal and press enter

899. echo $(( I + 4 ))

899.1

It should say, bash: 15: command not found. It replaced the command with the result of the calculation. Effectively, trying to run 15 as a command. Enter the same command, but put echo in front of it. The command was $(( I + 4 ))

HINTS

Type echo $(( I + 4 )) in the terminal and press enter

902. echo $I

902.1

Again, it replaced the calculation with the result. So it was basically the same as if you entered echo 15. Use echo to print I to the screen again.

HINTS

Type echo $I in the terminal and press enter

905. J=$(( I - 6 ))

905.1

It should still have printed 11 for I. See the hints if it didn't. These double parenthesis with a $ are how you can assign a variable to some calculation. In the terminal, create a J variable, and use the $(( ... )) syntax to set its value to I - 6.

HINTS

If it didn't print 11 for I, enter I=11 to set it to 11
Type J=$(( I - 6 )) in the terminal and press enter

908. echo $J

908.1

Use echo to print J.

HINTS

Here's an example: echo $<variable>
Type echo $J in the terminal and press enter

911. echo $(( J * 5 + 25 ))

911.1

J should equal 5. For some more practice, use echo to print the value J * 5 + 25.

HINTS

Type echo $(( J * 5 + 25 )) in the terminal and press enter

912. echo $J

912.1

It should have printed 50. Print J with echo again.

HINTS

Here's an example: echo $<variable>
Type echo $J in the terminal and press enter

913. declare -p

913.1

So, as a reminder, (( ... )) will perform a calculation or operation and output nothing. $(( ... )) will replace the calculation with the result of it. You made a few variables in this shell, view them with declare -p.

HINTS

Type declare -p in the terminal and press enter

914. declare -p J

914.1

declare can be used to create variables, but you are just going to use it to view them for now. If you scroll up a little, you should find your I and J variables in there. View J with declare -p J.

HINTS

Type declare -p J in the terminal and press enter

916. declare -p RANDOM

916.1

I saw RANDOM in that list, too. View it with declare -p <variable> like you did for J.

HINTS

Type declare -p RANDOM in the terminal and press enter

918. echo $(( RANDOM % 75 ))

918.1

Okay, I think I finally know how to get the random number for the Bingo Number Generator. Use echo and RANDOM % 75 to print a random number in the terminal.

HINTS

Use the $(( ... )) syntax to calculate the random number
Here's an example: echo $(( <calculation> ))
Type echo $(( RANDOM % 75 )) in the terminal and press enter

920. echo $(( RANDOM % 75 + 1 ))

920.1

One tiny problem, that calculation will give a number between 0 and 74. Enter the same command in the terminal, but add 1 to the calculation to get a random number between 1 and 75.

HINTS

Type echo $(( RANDOM % 75 + 1 )) in the terminal and press enter

928. Set NUMBER=$(( RANDOM % 75 + 1))

928.1

Back in your bingo.sh script, change the NUMBER variable so that it starts as a random number between 1 and 75 using the syntax you have been practicing.

HINTS

Change the NUMBER variable to the result of the calculation RANDOM % 75 + 1
Use the $(( ... )) syntax to make the calculation
It should look like this: NUMBER=$(( RANDOM % 75 + 1 ))

930. run ./bingo.sh

930.1

Run your script a few times in a row to make sure it's working.

HINTS

Type ./bingo.sh in the terminal and press enter
Make sure you are in the project folder first
Run it at least two times in a row

940. Add TEXT variable

940.1

Next, create a TEXT variable and set the value to "The next number is, ". When the script is finished, the output will be something like The next number is B:15.

HINTS

Make sure there's a space after the comma
Add TEXT="The next number is, " to the bingo.sh file

945. help let

945.1

The letter that goes with the random number depends on what the number is. If it's 15 or less, it will be a B. I saw some comparisons in the help let menu, take a look at it again.

HINTS

Type help let in the terminal and press enter

950. Add first if <= 15

950.1

You used the double square brackets with your if statement in the last program, but you can use the double parenthesis with these operators as well. In your script, create an if statement that uses double parenthesis for the condition. Check if the number variable is less than or equal to 15. If it is, use your two variables to print The next number is, B:<number>.

HINTS

Make sure you only have two echo statements in your script, the title being one of them
Here's an example of how your if statement should look:

if (( CONDITION ))
then
  STATEMENTS
fi

The condition you want is (( NUMBER <= 15 ))
In the statements area, use echo and your two variables to print The next number is, B:<number>
The statements area should look like this: echo $TEXT B:$NUMBER
The whole if statement should look like this:

if (( NUMBER <= 15 ))
then
  echo $TEXT B:$NUMBER
fi

960. Add elif -le 30

960.1

if statements can have an "else if" area like this:

if (( CONDITION ))
then
  STATEMENTS
elif [[ CONDITION ]]
then
  STATEMENTS
fi

Using the double square brackets this time, add an elif condition that checks if the number variable is less than or equal to 30. If it is, use your two variables again to print The next number is, I:<number>

HINTS

View the help test menu to see the operators you can use with the double square brackets
The condition you want is [[ $NUMBER -le 30 ]]. Don't forget the $
In the statements area, use echo and your two variables to print The next number is, I:<number>
The statements area should look like this: echo $TEXT I:$NUMBER
The elif area should look like this:

elif [[ $NUMBER -le 30 ]]
then
  echo $TEXT I:$NUMBER
fi

The whole if statement should look like this:

if (( NUMBER <= 15 ))
then
  echo $TEXT B:$NUMBER
elif [[ $NUMBER -le 30 ]]
then
  echo $TEXT I:$NUMBER
fi

970. Add elif < 46

970.1

You can add as many elif sections to an if statement as you want. Add another elif, below the last, one that uses the double parenthesis to check if the number variable is less than 46. If it is, use your two variables to print The next number is, N:<number>

HINTS

View the help let menu to see the operators you can use with the double parenthesis
The operator you want it <
You can add another elif like this:

if CONDITION
then
  STATEMENTS
elif CONDITION
then
  STATEMENTS
elif CONDITION
then
  STATEMENTS
fi

The condition you want is (( NUMBER < 46 ))
In the statements area, use echo and your two variables to print The next number is, N:<number>
The statements area should look like this: echo $TEXT N:$NUMBER
This elif area should look like this:

elif (( NUMBER < 46 ))
then
  echo $TEXT N:$NUMBER
fi

The whole if statement should look like this:

if (( NUMBER <= 15 ))
then
  echo $TEXT B:$NUMBER
elif [[ $NUMBER -le 30 ]]
then
  echo $TEXT I:$NUMBER
elif (( NUMBER < 46 ))
then
  echo $TEXT N:$NUMBER
fi

980. Add elif -lt 61

980.1

Run your script if you want to see the output. It should print one of the sentences if the random number is less than 46. It may take a couple tries. Add another elif, below the last one, that uses double square brackets to check if the number variable is less than 61. If it is, use your two variables to print The next number is, G:<number>

HINTS

View the help test menu to see the operators you can use with the double square brackets
The operator you want it -lt
The condition you want is [[ $NUMBER -lt 61 ]]. Don't forget the $
The statements area should look like this: echo $TEXT G:$NUMBER
This elif area should look like this:

elif [[ $NUMBER -lt 61 ]]
then
  echo $TEXT G:$NUMBER
fi

The whole if statement should look like this:

if (( NUMBER <= 15 ))
then
  echo $TEXT B:$NUMBER
elif [[ $NUMBER -le 30 ]]
then
  echo $TEXT I:$NUMBER
elif (( NUMBER < 46 ))
then
  echo $TEXT N:$NUMBER
elif [[ $NUMBER -lt 61 ]]
then
  echo $TEXT G:$NUMBER
fi

990. Add else

990.1

One more case to handle. Add an else at the bottom of the if that uses your two variables to print The next number is, O:<number>.

HINTS

View the if/else in your countdown.sh file to see how you did it before
You don't need a condition or the then on this one
Here's an example:

if CONDITION
then
  STATEMENTS
elif CONDITION
then
  STATEMENTS
...
else
  STATEMENTS
fi

The else area should look like this:

else
  echo $TEXT O:$NUMBER

The whole if should look like this:

if (( NUMBER <= 15 ))
then
  echo $TEXT B:$NUMBER
elif [[ $NUMBER -le 30 ]]
then
  echo $TEXT I:$NUMBER
elif (( NUMBER < 46 ))
then
  echo $TEXT N:$NUMBER
elif [[ $NUMBER -lt 61 ]]
then
  echo $TEXT G:$NUMBER
else
  echo $TEXT O:$NUMBER
fi

1000. ./bingo.sh

1000.1

Run your script a few times and make sure it's working.

HINTS

Type ./bingo.sh in the terminal and press enter
Make sure you are in the project folder first
Run it at least two times in a row

1010. touch fortune.sh

1010.1

I think the generator is done 😄 The next project is a fortune teller. Use the touch command to create fortune.sh in the same folder as the other scripts.

HINTS

Type touch fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1020. chmod +x fortune.sh

1020.1

Give your file executable permissions.

HINTS

Use the chmod command with the +x flag
Here's an example chmod <permissions> <filename>
You previously used chmod +x bingo.sh
Type chmod +x fortune.sh in the terminal and press enter

1030. Add shebang

1030.1

Add a shebang at the top of your new file that uses bash again.

HINTS

A shebang looks like this: #!<path_to_interpreter>
Enter which bash in the terminal to see the path to bash
Look at the shebang in one of your other scripts to get the syntax
It should look like this: #!/bin/bash
Add #!/bin/bash at the top of your fortune.sh file

1040. Add comment

1040.1

Add comment Program to tell a persons fortune

HINTS

Comments look like this: # <comment>
Add #Program to tell a persons fortune below the shebang
Capitalization matters

1050. Add echo "title"

1050.1

Add a title for this one like the others. This one should say ~~ Fortune Teller ~~. Don't forget the empty line before and after it.

HINTS

Print the whole title and the empty lines with a single echo command
Use the echo command with the -e flag and the new line (\n) character
Don't forget to put it in double quotes
Take a look at one of the title's from a previous file for a hint
Here's an example: echo -e "\n<message>\n"
You previously used echo -e "\n~~ Bingo Number Generator ~~\n"
Add echo -e "\n~~ Fortune Teller ~~\n" below the comment of your fortune.sh file

1060. ./fortune.sh

1060.1

Run the file once to make sure it's working.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1070. ARR=("a" "b" "c")

1070.1

This program will have an array of responses. One will be printed randomly after a user inputs a question. Practice first 😄 In the terminal, create an array like this: ARR=("a" "b" "c")

HINTS

Type the suggested command in the terminal
Type ARR=("a" "b" "c") in the terminal and press enter

1080. echo ${ARR[1]}

1080.1

Each variable in the array is like any other variable, just combined into a single variable. In the terminal, print the second item in the array with echo ${ARR[1]}. Note that the first item would be index zero.

HINTS

Type echo ${ARR[1]} in the terminal

1090. echo ${ARR[@]}

1090.1

If you recall, you were able to print all the arguments to your countdown.sh script with echo $*. echo $@ would have worked as well. Similarly, you can use the * or @ to print your whole array. In the terminal, use echo to print all the items in your array.

HINTS

Here's an example echo ${ARR[<index>]}
Type echo ${ARR[@]} in the terminal and press enter

1100. declare -p ARR

1100.1

The variable must be in that declare list. View your array variable using the declare command and the -p flag.

HINTS

Here's an example: declare -p <variable>
Type declare -p ARR in the terminal

1110. Add RESPONSES array

1110.1

The -a next to it stands for array. In your script, create an array named RESPONSES. Give it these six values: Yes, No, Maybe, Outlook good, Don't count on it, and Ask again later.

HINTS

Here's an example: VARIABLE=(value value ...)
Make sure any values with spaces are in proper quotes
You created your other array with ARR=("a" "b" "c")
Add RESPONSES=("Yes" "No" "Maybe" "Outlook good" "Don't count on it" "Ask again later") in your script

1120. echo ${RESPONSES[5]}

1120.1

In your script, use echo to print the last item in the array.

HINTS

Here's an example echo ${ARR[<index>]}
Remember that the first item starts at zero
Add echo ${RESPONSES[5]} to your fortune.sh file

1130. ./fortune.sh

1130.1

Run it to see the output.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1140. Add N=$(( RANDOM % 6 ))

1140.1

You will randomly print one of the values. In your script, create a variable named N. Set it equal to a random number between 0 and 5, the first and last index of the array.

HINTS

Use the modulus (%) operator and 6 to get a number between 0 and 5
Look at the random number you created in the bingo.sh file for a hint
Here's an example: VARIABLE=$(( <calculation> ))
Calculate a random number in the range you want with RANDOM % 6
Add N=$(( RANDOM % 6 )) to the script

1150. Change to echo ${RESPONSES[$N]}

1150.1

Change your echo command to print the item in the array whose index is the random number you generated.

HINTS

Use your $N variable as the index where you print an item from the array
Don't forget that scripts run from top to bottom, so you can't use any variables before they are created
Change the echo line to echo ${RESPONSES[$N]}

1160. help

1160.1

You will create a function to generate an answer. Check the help menu to see if you can find anything.

HINTS

Enter the suggested command in the terminal
Type help in the terminal

1170. help function

1170.1

See any that might help? There's one that says function. See if you can find out more about it.

HINTS

Use the help command to find out more
Here's an example: help <command>
Type help function in the terminal

1180. Add GET_FORTUNE function

1180.1

It looks like you can create a function like this:

FUNCTION_NAME() {
  STATEMENTS
}

Add an empty function named GET_FORTUNE to your script. Make sure the response you are printing is the last thing in the script.

HINTS

Add this to your script:

GET_FORTUNE() {}

Your echo ${RESPONSES[$N]} command should be at the bottom of the file

1190. Add echo Ask a yes or no question

1190.1

In your function, use echo to print Ask a yes or no question:

HINTS

Your function should look like this:

GET_FORTUNE() {
  echo Ask a yes or no question:
}

Your echo ${RESPONSES[$N]} command should be at the bottom of the file

1200. Add GET_FORTUNE function call

1200.1

Call your function by putting the name of it below where you create it. No $ needed. Make sure the response you are printing is at the bottom of the file.

HINTS

Add GET_FORTUNE below where you create your function to call it
Your echo ${RESPONSES[$N]} command should be at the bottom of the file

1210. ./fortune.sh

1210.1

Run your script to make sure it's working.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1220. Add read QUESTION

1220.1

In your function after you print the sentence, use read to get user input into a variable named QUESTION.

HINTS

Add read QUESTION to your function below the echo
Your function should look like this:

GET_FORTUNE() {
  echo Ask a yes or no question:
  read QUESTION
}

Your echo ${RESPONSES[$N]} command should be at the bottom of the file

1230. ./fortune.sh

1230.1

Run the script again to test it out. Enter a question when it asks.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1240. help

1240.1

I want to make sure the input is a question. You are going to add a loop that asks for input until the input ends with a question mark. View the help menu to see if you can find an appropriate loop.

HINTS

Type help in the terminal and press enter

1250. help until

1250.1

View more about that until command. That might be the one to use here.

HINTS

Use help <command> to view more about a command
Type help until in the terminal and press enter

1260. Add until loop

1260.1

The until loop is very similar to the while loop you used. It will execute the loop until a condition is met. Here's an example:

until [[ CONDITION ]]
do
  STATEMENTS
done

Add an until loop below your function. Use the double brackets to check if QUESTION is equal to test?. Move the GET_FORTUNE function call to the statements area of the loop. It should run the function until you input test? as the question.

HINTS

View the help [[ or help test menu to see if you can find the operator to use
You want the == operator
The condition should look like this: [[ $QUESTION == test? ]]
Your until loop should look like this:

until [[ $QUESTION == test? ]]
do
  GET_FORTUNE
done

You should only call the GET_FORTUNE function once
Your echo ${RESPONSES[$N]} command should be at the bottom of the file

1270. ./fortune.sh

1270.1

Run the script and enter something other than test?. Then enter test? after it asks for a question the second time.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1280. help [[ expression ]]

1280.1

View that help [[ expression ]] menu again. You need to find out how to test if the input ends with a question mark (?).

HINTS

Type help [[ or help [[ expression ]] in the terminal and press enter

1290. [[ hello == hello ]]; echo $?

1290.1

Let's play with these again. You can test if two strings are the same with ==. In the terminal, use the [[ ... ]]; echo $? syntax you used before to test if hello is equal to hello.

HINTS

Be sure to use the == operator
Type [[ hello == hello ]]; echo $? in the terminal and press enter

1300. [[ hello == world ]]; echo $?

1300.1

Exit status of 0, it was true. Using the same syntax, test if hello is equal to world.

HINTS

Use the [[ ... ]]; echo $? syntax
Be sure to use the == operator
Type [[ hello == world ]]; echo $? in the terminal and press enter

1310. [[ hello =~ el ]]; echo $?

1310.1

False. An important operator in that menu is =~. It allows for pattern matching. Using the same syntax but with this operator, check if hello contains the pattern el.

HINTS

Use the [[ ... ]]; echo $? syntax
Use the =~ operator with it
Type [[ hello =~ el ]]; echo $? in the terminal and press enter

1320. [[ "hello world" =~ "lo wor" ]]; echo $?

1320.1

True. The condition was checking for el within the word hello. Using the same syntax, check if hello world contains the pattern lo wor. You will need to put them both in quotes so it recognizes the spaces.

HINTS

Use the [[ ... ]]; echo $? syntax
Use the =~ operator with it
Type [[ "hello world" =~ "lo wor" ]]; echo $? in the terminal and press enter

1330. [[ "hello world" =~ ^h ]]; echo $?

1330.1

Your patterns have been checking for literal matches, el and lo wor. You can use regular expression characters as well, but you can't put the pattern in quotes when you do. Using the same syntax, check if hello world starts with an h by using ^h as the pattern.

HINTS

Make sure not to use quotes around the pattern when using regex characters it
Type [[ "hello world" =~ ^h ]]; echo $? in the terminal

1340. [[ "hello world" =~ ^h.+d$ ]]; echo $?

1340.1

Do it again, but use ^h.+d$ as the pattern to see if the string starts with an h, has at least one character after it, and ends with a d.

HINTS

Use the [[ ... ]]; echo $? syntax again
Check if hello world contains the suggested pattern
Make sure not to use quotes around the pattern when using regex characters it
Type [[ "hello world" =~ ^h.+d$ ]]; echo $? in the terminal

1350. VAR="hello world"

1350.1

In the terminal, create a variable named VAR that equals hello world.

HINTS

Type VAR="hello world" in the terminal

1360. echo $VAR

1360.1

Use echo to print the variable you just created.

HINTS

Type echo $VAR in the terminal

1370. [[ $VAR == "hello world" ]]; echo $?

1370.1

Using the [[ ... ]]; echo $? syntax, check if your variable is equal to hello world.

HINTS

Check the help [[ menu to find the operator to use
It's the == operator
You want to check if $VAR == "hello world"
Type [[ $VAR == "hello world" ]]; echo $? in the terminal

1380. [[ $VAR =~ ?$ ]; echo $?

1380.1

Using the same syntax, check if your variable ends with ? by using the pattern \?$.

HINTS

Be sure to use the pattern matching operator
It's the =~ operator
You want to check if $VAR =~ \?$
Type [[ $VAR =~ \?$ ]]; echo $? in the terminal

1385. [[ test? =~ ?$ ]; echo $?

1385.1

It doesn't end with ?. Just to make sure I don't have the pattern wrong, check if test? ends with ?.

HINTS

Use the same [[ ... ]]; echo $? syntax you have been using
Use the \?$ pattern to see if a string ends with ?
Make sure you're using the pattern matching operator =~
You want to check if test? =~ \?$
Type [[ test? =~ \?$ ]]; echo $? in the terminal

1390. Change until condition

1390.1

I think that will work. Back in your script, change the until condition to see if your variable ends with ?.

HINTS

Use the pattern matching operator with \?$
It's the =~ operator
Your condition should look like this: [[ $QUESTION =~ \?$ ]]
Make sure there's spaces inside the brackets and around the operator

1400. ./fortune.sh

1400.1

Run the script and input something that doesn't end with ? the first time, then something that does the second.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1410. Add if to GET_FORTUNE

1410.1

I know that it asks the same thing if the input isn't what you want. You should let users know that it needs to end with ?. Add an if condition in your function that checks if [[ ! $1 ]]. Put the existing echo statement in the then area and make sure the existing read is below the whole if condition.

HINTS

Here's an example:

if [[ CONDITION ]]
then
  STATEMENTS
fi

read QUESTION

Your function should look like this:

function GET_FORTUNE() {
  if [[ ! $1 ]]
  then
    echo Ask a yes or no question:
  fi

  read QUESTION
}

1412. Add else to if [[ ! $1 ]]

1412.1

You can pass arguments to functions like you did with your script. This condition will check if one isn't passed and print the sentence. Add an else to your if. Use echo to print Try again. Make sure it ends with a question mark: if the condition fails.

HINTS

Here's an example:

if [[ CONDITION ]]
then
  STATEMENTS
else
  STATEMENTS
fi

Your if condition should look like this:

if [[ ! $1 ]]
then
  echo Ask a yes or no question:
else
  echo Try again. Make sure it ends with a question mark:
fi

1413. Add argument to function call

1413.1

Now, your function will print one thing if you pass it any argument, and something else if not. In the until loop, add again as an argument to where you call the function.

HINTS

Here's an example: FUNCTION_NAME argument
Your function call should look like this: GET_FORTUNE again
Your until loop should look like this:

until [[ $QUESTION =~ \?$ ]]
do
  GET_FORTUNE again
done

1416. Add Initial function call

1416.1

Now, each time the function is called in the until loop, it will pass again as an argument and print the Try again... sentence. Before your until loop, call the function without an argument so the first time it runs, it prints the initial sentence.

HINTS

Add GET_FORTUNE before the until loop

1420. ./fortune.sh

1420.1

Run the script and enter something without a question mark when it asks the first time. Use a question mark the second time.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1425. Add line break in front of response

1425.1

Awesome. One last thing. Add an empty line in front of where you print the response.

HINTS

Change the existing echo ${RESPONSES[$N]} line
Use the -e flag and the new line (\n) character with the echo statement
Make sure to use quotes so it prints the new line
Run the script and see if it's working
The suggested command should look like this: echo -e "\n${RESPONSES[$N]}"

1428. ./fortune.sh

1428.1

Run the script one more time to see if you like the output.

HINTS

Type ./fortune.sh in the terminal and press enter
Make sure you are in the project folder first

1430. touch five.sh

1430.1

Excellent. One last program to make. Use touch to create a new file named five.sh in the same folder as the others.

HINTS

Type touch five.sh in the terminal and press enter
Make sure you are in the project folder first

1440. chmod +x five.sh

1440.1

Give your file executable permissions.

HINTS

Use the chmod command with the +x flag
Here's an example chmod <permissions> <filename>
You previously used chmod +x fortune.sh
Type chmod +x five.sh in the terminal and press enter

1450. Add shebang

1450.1

Add a shebang to the new script that uses bash like the others.

HINTS

A shebang looks like this: #!<path_to_interpreter>
Enter which bash in the terminal to see the path to bash
Look at the shebang in one of your other scripts to get the syntax
It should look like this: #!/bin/bash
Add #!/bin/bash at the top of your five.sh file

1460. Add comment

1460.1

Add a comment below the shebang that says, Program to run my other four programs

HINTS

Comments look like this: # <comment>
Add # Program to run my other four programs below the shebang
Capitalization matters

1470. Add ./questionnaire.sh

1470.1

This program will run all the programs you made so far consecutively. Add the command to run the questionnaire.sh file.

HINTS

The command should look like how you would execute the file in the terminal
Add ./questionnaire.sh to the five.sh file

1480. ./five

1480.1

Run the file to see if it works. Enter input when it asks.

HINTS

Type ./five.sh in the terminal and press enter
Make sure you are in the project folder first

1490. Add the rest of the scripts

1490.1

Add commands to run the rest of your scripts in the file. They should be in this order: questionnaire, countdown, bingo, and fortune. Don't forget that your countdown.sh file needs an argument, so put a 3 next to it.

HINTS

Your five.sh file should have these commands:

./questionnaire.sh
./countdown.sh 3
./bingo.sh
./fortune.sh

1500. Clear

1500.1

Okay, use clear to empty out what's in the terminal before the big moment.

HINTS

Type clear in the terminal

1510. ./five

1510.1

Run the script and enter input when it asks.

HINTS

Type ./five.sh in the terminal and press enter
Make sure you are in the project folder first

1520. help

1520.1

Cool. I think all the scripts are done. View the help menu again I want to explore one more thing.

HINTS

Type help in the terminal and press enter

1530. help type

1530.1

View more about that type command.

HINTS

Use help <command> to find out more about a command
Type help type in the terminal and press enter

1540. type echo

1540.1

It says you can view the type of a command with type <command>. Just for fun, lets take a look at the type of a few different commands. View the type of echo.

HINTS

Type type echo in the terminal and press enter

1550. type read

1550.1

View the type of the read command.

HINTS

Type type read in the terminal and press enter

1560. type if

1560.1

View the type of if

HINTS

Type type if in the terminal and press enter

1570. type then

1570.1

View the type of then

HINTS

Type type then in the terminal and press enter

1580. type bash

1580.1

Those were all from the help menu and described as a shell builtin or shell keyword. View the type of bash

HINTS

Type type bash in the terminal and press enter

1590. type psql

1590.1

That's the location of the bash command. View the type of psql.

HINTS

Type type psql in the terminal and press enter

1600. type ./five.sh

1600.1

It's showing the location of the commands. View the type of your ./five.sh file.

HINTS

Type type ./five.sh in the terminal and press enter

1610. exit

1610.1

Last step, close the terminal with the exit command. Thanks and happy coding!

HINTS

Type exit in the terminal and press enter

Files

TUTORIAL.md

Latest commit

History

TUTORIAL.md

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Learn Bash Scripting by Building Five Programs

10. Start the Terminal

10.1

HINTS

20. touch questionnaire.sh

20.1

HINTS

30. Add echo questionnaire

30.1

HINTS

35. sh questionnaire.sh

35.1

HINTS

40. bash questionnaire.sh

40.1

HINTS

50. which bash

50.1

HINTS

60. Add shebang

60.1

HINTS

70. ./questionnaire

70.1

HINTS

80. ls -l

80.1

HINTS

90. chmod +x questionnaire.sh

90.1

HINTS

100. ls -l

100.1

HINTS

110. ./questionnaire

110.1

HINTS

140. Add ls -l

140.1

HINTS

150. ./questionnaire

150.1

HINTS

160. Delete all - shebang

160.1

HINTS

170. Add QUESTION1 variable

170.1

HINTS

180. Add echo $QUESTION1

180.1

HINTS

190. ./questionnaire

190.1

HINTS

200. Add read NAME

200.1

HINTS

210. Add echo Hello $NAME

210.1

HINTS

220. ./questionnaire

220.1

HINTS

230. Add QUESTION2 variable

230.1

HINTS

240. Add echo $QUESTION2

240.1

HINTS

250. Add read LOCATION

250.1

HINTS

260. Add echo Hello $NAME from $LOCATION

280. Add echo " Questionnaire "

320. Add echo -e \n Questionnaire \n

326. Change to echo -e "\n Questionnaire \n"