#$!/$bin$/$bash

# Define the input file

input$\_$file$=$"email$\_$list.txt$"$

# Write a regular expression to match valid email addresses.

# An email consists of these parts: username, @ symbol, domain name, top$-$level domain $($TLD$)($e$.$x$.$user@domain.tld$)$

# Email rules:

# $1.$ Username consists of alphanumeric characters, $.,,,\%,+,$ and $-$

# $2.$ Usernames cannot start or end with a special character $(.\_++-)$

# $3.$ Domain name consists of alphanumeric characters, $.,$ and $-$

# $4.$ Domain name cannot start or end with a special character $(.-)$

# $5.$ TLD consists of lowercase alphabetic characters and has a length of $2$ or more

# $6.$ The @ symbol separates the username and the domain name

# $7.$ The $.$ separates the domain name and the top$-$level domain $($TLD$)$

# $8.$ The regular expression should match the entire email address

email$\_$regex$=$

# use grep to filter and display valid email addresses using the $email$\_$regex variable

valid$\_$email$\_$count$=$

# use grep to filter and display invalid email addresses using the $email$\_$regex variable

invalid$\_$emails$=$

echo "Number of valid email addresses: $valid$\_$email$\_$count"

echo "Invalid email addresses: $"$

echo $"$$invalid$\_$emails"