This script adds a new SFTP user with only sftp access.  Refer to this post on setting up a SFTP server.

Download script

wget www.incredigeek.com/home/downloads/scripts/sftpUserAdd.sh

Make executable

chmod +x sftpUserAdd.sh

Run with the new user you want to create.

./sftpUserAdd.sh sftpUsername

You may need to edit the script and modify the location parameters.

#!/bin/bash
# Automatically setup and add SFTP user
# Script creates new user and setups permissions
newUser=$1
sftpDir="/sftp/"
if grep -q ${newUser} /etc/passwd ;then
        echo ${newUser} Already exsists.  Aborting!
        exit 1
else
        mkdir -p ${sftpDir}/${newUser}/files
        useradd -g sftpusers -d ${sftpDir}/${newUser}/files -s /sbin/nologin ${newUser}
        passwd ${newUser}
        chown ${newUser}:sftpusers /sftp/CareMark/files
fi