User account management script in Bash Scripting - Mini Project: Build & Apply

User account management script

📖 Scenario: You are a system administrator who needs to manage user accounts on a Linux server. You want to automate the process of checking user accounts and their statuses.

🎯 Goal: Create a Bash script that stores a list of user accounts with their statuses, sets a status filter, filters the users based on that status, and then prints the filtered list.

📋 What You'll Learn

Create an associative array called users with usernames as keys and their statuses as values.

Create a variable called filter_status to hold the status to filter users by.

Use a for loop to iterate over the users array and select users whose status matches filter_status.

Print the filtered usernames and their statuses.

💡 Why This Matters

🌍 Real World

System administrators often need to manage user accounts and their statuses on servers. Automating this with scripts saves time and reduces errors.

💼 Career

Knowing how to write scripts for user account management is valuable for roles in IT support, system administration, and DevOps.

1

Create the user accounts data

Create an associative array called users with these exact entries: alice with status active, bob with status inactive, carol with status active, and dave with status inactive.

Bash Scripting

# Create the associative array users with usernames and statuses
# Your code here

Hint

Use declare -A users to create an associative array in Bash.

2

Set the status filter

Create a variable called filter_status and set it to the string active.

Bash Scripting

declare -A users=( [alice]=active [bob]=inactive [carol]=active [dave]=inactive )
# Set the filter_status variable to 'active'
# Your code here

Hint

Assign the string active to the variable filter_status.

3

Filter users by status

Use a for loop with the variable user to iterate over the keys of the users array. Inside the loop, use an if statement to check if the user's status matches filter_status. If it matches, add the user and their status to a new associative array called filtered_users.

Bash Scripting

declare -A users=( [alice]=active [bob]=inactive [carol]=active [dave]=inactive )
filter_status="active"
# Create an empty associative array filtered_users
declare -A filtered_users=()
# Use a for loop to iterate over users and filter by filter_status
# Your code here

Hint

Use for user in "${!users[@]}" to loop over keys of an associative array.

4

Print the filtered users

Use a for loop with the variable user to iterate over the keys of the filtered_users array. Inside the loop, print the username and their status in the format: user: status.

Bash Scripting

declare -A users=( [alice]=active [bob]=inactive [carol]=active [dave]=inactive )
filter_status="active"
declare -A filtered_users=()
for user in "${!users[@]}"; do
    if [[ "${users[$user]}" == "$filter_status" ]]; then
        filtered_users[$user]="${users[$user]}"
    fi
done
# Print each user and their status from filtered_users
# Your code here

Hint

Use echo "$user: ${filtered_users[$user]}" inside the loop to print each filtered user.

Practice

1. What is the main purpose of a bash script that manages user accounts with commands like useradd and userdel?

easy

A. To change the system hostname

B. To automate adding, deleting, and listing users on the system

C. To update software packages automatically

D. To monitor network traffic

Solution

1. Step 1: Understand the commands used

   The commands useradd and userdel are specifically for managing user accounts on Linux systems.

2. Step 2: Identify the script's goal

   Since the script uses these commands, its main purpose is to automate user account management tasks like adding, deleting, and listing users.

3. Final Answer:

   To automate adding, deleting, and listing users on the system -> Option B

4. Quick Check:

   User management commands = automate user tasks [OK]

Hint: Look for user management commands like useradd/userdel [OK]

Common Mistakes:

• Confusing user management with system updates
• Thinking it changes network settings
• Assuming it modifies system hostname

2. Which of the following is the correct syntax to add a new user named alice in a bash script?

easy

A. createuser alice

B. adduser alice

C. newuser alice

D. useradd alice

Solution

1. Step 1: Recall the standard command for adding users

   The standard Linux command to add a user is useradd.

2. Step 2: Match the command with the username

   Using useradd alice correctly adds a user named alice.

3. Final Answer:

   useradd alice -> Option D

4. Quick Check:

   Standard add user command = useradd [OK]

Hint: Remember: useradd is the standard command to add users [OK]

Common Mistakes:

• Using adduser which may not be available on all systems
• Typing createuser or newuser which are invalid commands
• Confusing commands with other system utilities

3. What will be the output of this bash snippet if the script is run with root privileges?

if id "bob" &>/dev/null; then
  echo "User exists"
else
  echo "User does not exist"
fi

medium

A. User does not exist

B. User exists

C. Syntax error

D. Permission denied

Solution

1. Step 1: Understand the id command usage

   The command id "bob" checks if user bob exists. If bob does not exist, it returns an error.

2. Step 2: Analyze the if condition and output

   The script redirects errors to /dev/null, so if bob does not exist, the else branch runs, printing "User does not exist".

3. Final Answer:

   User does not exist -> Option A

4. Quick Check:

   id command fails = else branch runs [OK]

Hint: id command success means user exists; else means no user [OK]

Common Mistakes:

• Assuming output shows error messages
• Thinking permission issues cause output
• Confusing command syntax with errors

4. Identify the error in this script snippet that tries to delete a user named charlie:

userdel charlie
if [ $? -eq 0 ]; then
  echo "User deleted"
else
  echo "Failed to delete user"
fi

medium

A. Missing sudo or root privileges to run userdel

B. Incorrect syntax for if statement

C. userdel command should be userremove

D. No error, script works fine

Solution

1. Step 1: Check command permissions

   The userdel command requires root privileges. Running it without sudo or as root will fail.

2. Step 2: Verify script syntax and commands

   The if statement syntax and command are correct, but permission issues cause failure.

3. Final Answer:

   Missing sudo or root privileges to run userdel -> Option A

4. Quick Check:

   userdel needs root = permission error if missing [OK]

Hint: Remember: userdel needs root or sudo to succeed [OK]

Common Mistakes:

• Thinking userdel syntax is wrong
• Using wrong command name like userremove
• Ignoring permission requirements

5. You want to write a bash script that adds multiple users from a list in a file users.txt. Which script snippet correctly reads each username and adds the user, skipping empty lines?

hard

A. read users.txt | while read user; do
useradd $user
done

B. for user in $(cat users.txt); do
useradd $user
done

C. while read user; do
[ -z "$user" ] && continue
useradd "$user"
done < users.txt

D. cat users.txt | while useradd; do
echo $user
done

Solution

1. Step 1: Understand reading lines safely

   Using while read user reads each line safely, including spaces, and allows skipping empty lines.

2. Step 2: Check skipping empty lines and adding users

   The condition [ -z "$user" ] && continue skips empty lines. Then useradd "$user" adds the user correctly.

3. Final Answer:

   while read user; do [ -z "$user" ] && continue useradd "$user" done < users.txt -> Option C

4. Quick Check:

   Safe line read + skip empty + add user = while read user; do [ -z "$user" ] && continue useradd "$user" done < users.txt [OK]

Hint: Use while read and check empty lines to avoid errors [OK]

Common Mistakes:

• Using for loop with word splitting causing errors
• Incorrect pipe usage with cat and while
• Not skipping empty lines causing useradd errors