SHELL

bash conditional regex match

Just appreciate next solution example for your code implementation:
S=finding
if[[ "$S" == *ing ]]; then ...//some code run if string ends with 'ing'
More generally:
if[[ "string_to_check" == regex_patten ]]; then ...//some code

if regex bash

#ensure there are no quotes arround the regex
if [[ "${DOMAINS}" =~ *..+ ]]; then ...

using regex in bash conditional statement

pat="[0-9a-zA-Z ]"
if [[ $x =~ $pat ]]; then ...

bash regex if condition

Use following structure:
if [[ $digit =~ [0-9] ]]; then //run if a digit included in $digit string
    echo "$digit is a digit"
else
    echo "oops"
fi

bash if else regex

#!/bin/bash

if [[ "$date" =~ ^[0-9]{8}$ ]]; then
    echo "Valid date"
else
    echo "Invalid date"
fi