Scripting Basics

Question 1

How would you create a script that uses python?

Answer 1

!/usr/bin/python

print(‘Hello, World!’)

Question 2

What is the appropriate way to create a variable?
print the variable
How would you add the variable and put a suffix on it?

Answer 2

THIS_VARIABLE=’this’
echo “I like $THIS_VARIABLE stuff”
echo “I like ${THIS_VARIABLE}s. oops one extra ‘s’”

Question 3

Create a variable that contains the output of hostname and then print the variable

Answer 3

SERVER_NAME=hostname
echo ‘You are running this script on ${SERVER_NAME}’

or
SERVER_NAME=$(hostname)

Question 4

What can variables contain?
What can a variable start with?

Answer 4

digits, letters and underscores
They can start with Letters or Underscores but no digits

Question 5

What should you do to create a test?
Create a test to see if /etc/passwd exists
What does this return
Show all test you can perform
Read the manual for tests

Answer 5

[ -e /etc/passwd ]
This returns a 0 if it exists
If it doesn’t exist it returns a 1 if it exists
help test
man test

Question 6

Write a script to print two things if /etc/passwd exists

Create one for a variable you create is equal to ‘bash’

Answer 6

MY_VAR=’bash’

if [ -e /etc/passwd ]
then
echo ‘this’
echo ‘that’
fi

if [ ‘$MY_VAR’ = ‘bash’]
then
echo ‘this’’
else
echo ‘that’
fi

Question 7

Should you enclose variables in quotes?

Answer 7

Yes, this is to prevent unexpected side effects when performing conditional tests.

Question 8

When would you use elif?

Answer 8

Elif is used if instead of if because it won’t run unless the first if fails. If on the other hand will run everytime.

Question 9

Use a for loop

Answer 9

for COLOR in red green blue
do
echo ‘The color is $COLOR’
done

Question 10

What are Positional Parameters?

Use a positional argument in a script

Answer 10

Location of words in you commands. Parameter here just means word. From start to finish you will have $0 - $9

View the below command:
script.sh parameter1 parameter2 parameter3
script.sh $0
parameter1 $1
parameter2 $2
parameter3 $3

REMEMBER TO USE DOUBLE QUOTES
#!/bin/bash
echo “Locking password for $1”
passwd -l $1
./script.sh delsinm <- delsinm is parameter $1

YOU COULD EVEN JUST ASSIGNE IT TO A VALUE
USER=$1

Question 11

How would you create a for loop to cycle through all users that you’ve added as positional arguments

Answer 11

for USER in $@
do
passwd -l $USER
done

Question 12

How would you collect the input from someone asking for their username and storing it in a variable called USER

Answer 12

read -p “Enter a user name: “ USER
echo “Archiving $USER”