0x03-shell_variables_expansions

0x03. Shell, init files, variables and expansions

In this project, I learned about initialization files, local, global, and reserved variables and special parameters in the Shell. Furthermore, I practiced using expansions, performing arithmetic operations, and utilizing aliases.

TASKS

0. <o>

Create a script that creates an alias.

• Name: ls
• Value: rm *

1. Hello you

Create a script that prints hello user, where user is the current Linux user.

2. The path to success is to take massive, determined action

Add /action to the PATH. /action should be the last directory the shell looks into when looking for a program.

3. If the path be beautiful, let us not ask where it leads

Create a script that counts the number of directories in the PATH.

4. Global variables

Create a script that lists environment variables.

5. Local variables

Create a script that lists all local variables and environment variables, and functions.

6. Local variable

Create a script that creates a new local variable.

• Name: BEST
• Value: School

7. Global variable

Create a script that creates a new global variable.

• Name: BEST
• Value: School

8. Every addition to true knowledge is an addition to human power

Write a script that prints the result of the addition of 128 with the value stored in the environment variable TRUEKNOWLEDGE, followed by a new line.

9. Divide and rule

Write a script that prints the result of POWER divided by DIVIDE, followed by a new line.

• POWER and DIVIDE are environment variables

10. Love is anterior to life, posterior to death, initial of creation, and the exponent of breath

Write a script that displays the result of BREATH to the power LOVE

• BREATH and LOVE are environment variables
• The script should display the result, followed by a new line

11. There are 10 types of people in the world -- Those who understand binary, and those who don't

Write a script that converts a number from base 2 to base 10.

• The number in base 2 is stored in the environment variable BINARY
• The script should display the number in base 10, followed by a new line

12. Combination

Create a script that prints all possible combinations of two letters, except oo.

• Letters are lower cases, from a to z
• One combination per line
• The output should be alpha ordered, starting with aa
• Do not print oo
• Your script file should contain maximum 64 characters

13. Floats

Write a script that prints a number with two decimal places, followed by a new line.

The number will be stored in the environment variable NUM.

14. Decimal to Hexadecimal

Write a script that converts a number from base 10 to base 16.

• The number in base 10 is stored in the environment variable DECIMAL
• The script should display the number in base 16, followed by a new line

15. Everyone is a proponent of strong encryption

Write a script that encodes and decodes text using the rot13 encryption. Assume ASCII.

16. The eggs of the brood need to be an odd number

Write a script that prints every other line from the input, starting with the first line.

17. I'm an instant star. Just add water and stir.

Write a shell script that adds the two numbers stored in the environment variables WATER and STIR and prints the result.

• WATER is in base water
• STIR is in base stir.
• The result should be in base bestchol