Set up vsftpd for multiple users

setup-vsftpd.sh

#!/bin/bash
#
# This script is used to set up vsftpd for multiple virtual users with predefined passwords
# fetched from a text file. The vsftpd configuration file that is outputted enforces 
# FTP Explicit TLS for all client connections.
#
# The text file with predefined users and passwords must have the following format:
# <username>:<password>
# 
userfile=users.txt
wwwpath=/srv/ftp
configfile=/etc/vsftpd.conf
passwdfile=/etc/vsftpd.passwd
certfile=/etc/vsftpd.pem

if [ ! -f $userfile ]; then
    echo "The file $userfile is missing"
    exit
fi

if [ ! -d $wwwpath ]; then
    echo "The directory $wwwpath is missing"
    exit
fi

if [ "$(id -u)" != "0" ]; then
    echo "This script is designed to run as root"
    exit
fi

apt-get -y install vsftpd apache2-utils libpam-pwdfile

touch $passwdfile

while read userline
do
    if [ ${#userline} -gt 2 ]; then
        username=${userline%:*}
        password=${userline#*:}
        mkdir -p "$wwwpath/$username"
        htpasswd -bd $passwdfile $username $password
    fi
done < $userfile
chmod 600 $passwdfile

openssl req -x509 -nodes -days 730 -newkey rsa:1024 -keyout $certfile -out $certfile
chmod 600 $certfile

tee "$configfile" > /dev/null << EOF
anonymous_enable=NO
chroot_local_user=YES
connect_from_port_20=YES
guest_enable=YES
guest_username=www-data
hide_ids=YES
listen=YES
local_enable=YES
local_root=$wwwpath/\$USER
local_umask=0022
pam_service_name=vsftpd
secure_chroot_dir=/var/run/vsftpd
user_sub_token=\$USER
virtual_use_local_privs=YES
write_enable=YES
xferlog_enable=YES
ssl_enable=YES
allow_anon_ssl=NO
force_local_data_ssl=NO
force_local_logins_ssl=YES
ssl_tlsv1=YES
ssl_sslv2=NO
ssl_sslv3=NO
rsa_cert_file=$certfile
EOF
chmod 600 $configfile

tee "/etc/pam.d/vsftpd" > /dev/null << EOF
auth    required pam_pwdfile.so pwdfile $passwdfile
account required pam_permit.so
EOF