simple-sftp-server.sh

#!/bin/bash

config_directory="$(dirname "$(realpath "$0")")"
port=2222

while [[ "$#" -gt 0 ]]; do
    case "$1" in
        -c|--config-directory)
            config_directory="$2"
            shift
            shift
            ;;
        -p|--port)
            port="$2"
            shift
            shift
            ;;
    esac
done

if [[ ! -f "${config_directory}/host_key" ]]; then
    ssh-keygen -t rsa -b 4096 -f "${config_directory}/host_key" -N ''
fi

cat <<EOF >"${config_directory}/sshd_config"
Port	${port}
HostKey	${config_directory}/host_key
AuthorizedKeysFile	${config_directory}/authorized_keys
ChallengeResponseAuthentication	no
UsePAM	yes
AllowAgentForwarding	no
AllowTcpForwarding	no
PrintMotd	no
PidFile	${config_directory}/sshd.pid
Subsystem	sftp	internal-sftp
ForceCommand	internal-sftp
EOF

echo "Note: You may want to manually kill the remaining sshd processes for active sessions after you exit the main sshd process."
"$(type -p sshd)" -Def "${config_directory}/sshd_config"