```
#!/bin/bash

HOSTNAME=""
USERNAME=""
PASSWORD=""
DATABASE=""

# mysql or postgresql
SERVER_TYPE="postgresql"

BACKUP_DIR="/tmp/backup"
DAYS_TO_KEEP=7

export PGPASSWORD="$PASSWORD"

function init() {
  if [[ ! -d $BACKUP_DIR ]]; then
    echo
    echo "The directory $BACKUP_DIR not found!"
    echo
    exit 1
  else
    for (( i = 0; i < $DAYS_TO_KEEP; i++ )); do
      if [[ ! -d "$BACKUP_DIR/$i" ]]; then
        mkdir "$BACKUP_DIR/$i"
      fi
    done
  fi
}

function perform_backup() {
  echo "perform backup!"
  if [[ ! -d "$BACKUP_DIR/0" ]]; then
    mkdir "$BACKUP_DIR/0"
  fi

  if [ "$SERVER_TYPE" == "mysql" ]; then
  elif [ "$SERVER_TYPE" == "postgresql" ]; then
    pg_dump --host=$HOSTNAME --port=5432 --username=$USERNAME --no-password $DATABASE | xz -c > $BACKUP_DIR/0/$DATABASE-prod-$(date +\%Y\%m\%d-\%H\%M).sql.xz
  fi
}

function remove_expired_backup() {
  echo "remove expired backups!"
  for (( i = $DAYS_TO_KEEP-1; i>=0; i-- )); do
    mv "$BACKUP_DIR/$i" "$BACKUP_DIR/$((i+1))"
  done

  rm -rf "$BACKUP_DIR/$DAYS_TO_KEEP"
}


function upload_to_qiniu() {
  if [ -d "$BACKUP_DIR/1" ]; then
    echo "upload!"
  fi
}

init
remove_expired_backup
perform_backup
upload_to_qiniu
```