Backup script for SQLite databases

backup-db.rb

#!/usr/lib/env ruby

# Acquires a shared lock on a SQLite database file and copies it to a backup
# usage:  backup-db.rb DBFILE.db BACKUPFILE.db
# author:  William Benton ([email protected])
# Public domain.

require 'sqlite3'
require 'fileutils'

def backup_db(db_file, backup_file)
  begin
    db = SQLite3::Database.new(db_file)

    db.transaction(:immediate) do |ignored|
      # starting a transaction with ":immediate" means we get a shared lock
      # and thus any db writes (unlikely!) complete before we copy the file
      FileUtils.cp(db_file, backup_file, :preserve=>true)
    end
  ensure
    db.close
  end
end

backup_db(ARGV[0], ARGV[1])