Shell script to create user name

#!/bin/bash

function grep_user()
{
    
    
	R=`grep "^$1:" /etc/passwd | wc -l`
	echo $R
}

echo -n "input username:"

read USERNAME

RET=`grep_user $USERNAME`
echo "......return $RET ......."
if [ $RET -eq 1 ]
then
	echo "$USERNAME  exist"
else
	echo "$USERNAME not exist"
	echo "plz add a new user"
	sudo adduser $USERNAME
fi

Test Results