read -p "Enter your username:" username
if grep -q $username "$user.txt"
then
  echo "Username already exists. Try another one."
  exit
fi

read -s -p "Enter your password:" password
read -p "Enter your salary:" salary
read -p "Enter your e-mail:" email
if grep -q $email "$user.txt"
then
  echo "E-mail already exists.Try another one."
  exit
fi


if[-f$"user.txt"]
then
   if[-w$"user.txt]
   then
     echo $username $password $salary $email >> $"user.txt"
     echo "User saved."
   fi
fi

echo "USER LIST"

a=1
while readline;do
echo "$line"
a=$((a+1))
done<$"user.txt"