Why does a function in bash script throw syntax error as root (using sudo) while as standard user it works?

Question

I am working on a script and this contains a function to create a new user and this function needs to be run as root to work but when I run my script as:

sudo ./sample.sh

It throws the following error:

./sample: 3: Syntax error: "(" unexpected

But when I run it without sudo I get this output:

-
-
useradd: Permission denied.
useradd: cannot lock /etc/passwd; try again later.
chage: user 'yt' does not exist in /etc/passwd
chage: user 'yt' does not exist in /etc/passwd
-
-
sed: can't read /etc/sudoers: Permission denied
sed: can't read /etc/sudoers: Permission denied
-
-

Thus the script is working with my standard user (it's just a privilege problem). I don't understand why it is not working with sudo. I find in the internet that I need to export the function but still same problem, here's the script:

############create user Function#
#!/bin/bash
function user_create ()
{


        useradd -m -p '#SOME_PASSWD' -s /bin/bash $userName

        sudo chage  -m 5 -M 90 -I 30 -W 14  $userName
        sudo  chage --lastday 0  $userName
        echo ''
        echo '--------------------------------------------------------------------------------------------'
        echo -e '\e[32mPasswd set for \e[1m'$userName' for 90 days MAX | 5 days MIN\e[0m'
        echo -e '\e[32mPasswd is set to change the current passwd in next login for \e[1m' $userName
        echo -e '\e[0m--------------------------------------------------------------------------------------------'
        #User based policy#
        sed -i "#SOME_SED_COMMAND" /etc/sudoers
        sed -i "/#SOME_STRING/#NEW_STRING" /etc/sudoers

        echo -e '\e[33m'
        sudo cat /etc/sudoers | grep -i "$userName"
        echo -e '\e[0m'
        echo ''
        echo '------------------------------------------------------------------'
        echo -e '\e[1m\e[32mUser Privilege Set\e[0m'
        echo '------------------------------------------------------------------'

        return 0
}

export -f user_create

if [ -z $1 ]
then
        echo -e 'e\1[m e\[100m e\[33m Do you want to CREATE A NEW USER?e\[0m (y/n)'
        read createUser
        if [ $createUser = 'y' -o $createUser = 'Y' ]
        then
                echo 'Enter USER.NAME:::: First_Name.Last_Name'
                read userName
                user_create
        else
                echo ''
                echo '------------------------------------------------------------------'
                echo -e '\e[31mNO NEW USER added.\e[0m'
                echo '------------------------------------------------------------------'
        fi
else
        userName=$1
        User_Create

fi

Answer 1

Why does a funtion in bash script throws syntax error …?

The line

#!/bin/bash

has no effect - it would have to be the first line; so the script may from different environments be executed by different shells, some of which have an incompatible syntax.