Password not getting set for this user creation script

The following script is supposed to create a user and generate a random password on an Ubuntu machine:

#!/bin/bash

#Script should execute with sudo/root access
if [[ "${UID}" -ne 0 ]]
then
    echo "Please run with sudo or root"
    exit 1
fi

#User should provide atleast one argument as username else guide him
if [[ "${#}" -lt 1 ]]
then
    echo "Usage: ${0} USER_NAME [COMMENT]..."
    echo "Create a user with name USER_NAME and comments field of COMMENT"
    exit 1
fi

#Store 1st argument as user name
USER_NAME="${1}"

#In case of more than one argument, store it as account comments
shift
COMMENT="${@}"

#Create a password
 PASSWORD=$(date +%s%N)

#Create the user
useradd -c "$COMMENT" -m $USER_NAME

#Check if user is successfully created or not
if [[ $? -ne 0 ]]
then
    echo "The Account could not be created"
    exit 1
fi

#Set the password for the user
echo $PASSWORD | passwd --stdin $USER_NAME

#Check if password is successfully set or not
if [[ $? -ne 0 ]]
then
    echo "The password could not be set"
    exit 1
fi

#Force password change on first login
passwd -e $USER_NAME

#Display username, password and the host where the user was created
echo
echo "Username: $USER_NAME"
echo
echo "Password: $PASSWORD"
echo
echo "Hostname: $(hostname)"

Output:

root@Sengh:/home/sengh/scripts# bash user_create.sh singh this is a
passwd: unrecognized option '--stdin'
Usage: passwd [options] [LOGIN]

Options:
  -a, --all                     report password status on all accounts
  -d, --delete                  delete the password for the named account
  -e, --expire                  force expire the password for the named account
  -h, --help                    display this help message and exit
  -k, --keep-tokens             change password only if expired
  -i, --inactive INACTIVE       set password inactive after expiration
                                to INACTIVE
  -l, --lock                    lock the password of the named account
  -n, --mindays MIN_DAYS        set minimum number of days before password
                                change to MIN_DAYS
  -q, --quiet                   quiet mode
  -r, --repository REPOSITORY   change password in REPOSITORY repository
  -R, --root CHROOT_DIR         directory to chroot into
  -P, --prefix PREFIX_DIR       directory prefix
  -S, --status                  report password status on the named account
  -u, --unlock                  unlock the password of the named account
  -w, --warndays WARN_DAYS      set expiration warning days to WARN_DAYS
  -x, --maxdays MAX_DAYS        set maximum number of days before password
                                change to MAX_DAYS

The password could not be set