Simple Email Validator in Bash

email_validator_regex.sh

#!/bin/bash

validator() {
  printf "* %-48s" "$1"
  echo "$1" | egrep --quiet "^([A-Za-z]+[A-Za-z0-9]*((\.|\-|\_)?[A-Za-z]+[A-Za-z0-9]*){1,})@(([A-Za-z]+[A-Za-z0-9]*)+((\.|\-|\_)?([A-Za-z]+[A-Za-z0-9]*)+){1,})+\.([A-Za-z]{2,})+"
  [ $? -eq 0 ] && printf "\e[1;32m[pass]\e[m" || printf "\e[1;31m[fail]\e[m"
  echo
}

echo
echo "a simple email validator in shell"
echo
echo "online validator: http://emailregex.com/"
echo "RFC: http://emailregex.com/email-validation-summary/"
echo

echo
echo "### expected result: valid"
echo

validator "valid@example.com"
validator "vali.d@example.com"
validator "va-lid@example.com"
validator "v-a-l-i-d@example.com"
validator "v.a-lid@example.com"
validator "v.ali-d@example.com"
validator "v_ali-d@example.com"
validator "va_li-d@example.com"
validator "v_a_li_d@example.com"
validator "v.ali-d@example.com"
validator "v.ali.d@example.com"
validator "v0.ali.d@example.com"
validator "v0.ali.d1@example.com"
validator "valid@e-x_ample.com"
validator "valid@e.x-ample.c.om"
validator "valid@e.xample.c.a.tw"

echo
echo "### expected result: invalid"
echo

validator "-invalid@example.com"
validator ".invalid@example.com"
validator "_invalid@example.com"
validator "inv alid@example.com"
validator "invalid@exa mple.com"
validator "inv.-alid@example.com"
validator "inv-.-alid@example.com"
validator "invali-.-d@example.com"
validator "inval..id@example.com"
validator "inva--lid@example.com"
validator "inval_-id@example.com"
validator "inval-.id@example.com"
validator "invalid.@example.com"
validator "invalid_@example.com"
validator "invalid-@example.com"
validator "invalid.0@example.com"
validator "invalid.1@example.com"
validator "0.invali.d@example.com"
validator "0.invali.1@example.com"
validator "inv.ali.0d@example.com"
validator "invalid@example.c-.om"
validator "invalid@example._com"
validator "invalid@e-x._ample.com"
validator "invalid@e-.x_ample.com"
validator "invalid@e.-x_ample.com"
validator "invalid@example.c"
validator "invalid@example._"
validator "invalid@exampl.0e"
validator "invalid@exampl.e1"
validator "invalid@exampl.1"
validator "invalid@exampl.1a.b.c"

echo
echo "### END"
echo