Recipe 23.8. Automating Backups
Problem
You want to make a dated archive of a directory to burn to CD or otherwise store on backup media.
Solution
This script copies a directory to a timestamped backup. It reuses the File.versioned_ filename method defined in Recipe 6.14, so you can create multiple
backups in the same time period:
require 'fileutils'
def backup(from_dir, to_dir, time_format="-%Y%m%d")
from_path, from_name = File.split(from_dir)
now = Time.now.strftime(time_format)
Dir.mkdir(to_dir) unless File.exists? to_dir
unless File.directory? to_dir
raise ArgumentError, "Not a directory: #{to_dir}"
end
to = File.versioned_filename(File.join(to_dir, from_name + now))
FileUtils.cp_r(from_dir, to, :preserve=>true)
return to
end
# This method copied from "Backing Up to Versioned Filenames"
class File
def File.versioned_filename(base, first_suffix=".0")
suffix = nil
filename = base
while File.exists?(filename)
suffix = (suffix ? suffix.succ : first_suffix)
filename = base + suffix
end
return filename
end
end
# Create a dummy directory
Dir.mkdir('recipes')
# And back it up.
backup('recipes', '/tmp/backup') # => "/tmp/backup/recipes-20061031"
backup('recipes', '/tmp/backup') # => "/tmp/backup/recipes-20061031.0"
backup('recipes', '/tmp/backup', '-%Y%m%d-%H.%M.%S')
# => "/tmp/backup/recipes-20061031-20.48.56"
Discussion
The backup method recursively copies the contents of a directory into another directory, possibly on another filesystem. It uses the time-based scheme you specify along with versioned_filename to uniquely name the destination directory.
As written, the backup method uses a lot of space: every time you call it, it creates an entirely new copy of every file in the source directory. Fortunately, the technique has many variations. Instead of copying the files, you can make a timestamped tarball with the techniques from Recipe 12.10. You can archive the files to another computer with the techniques from Recipe 14.11 (although to save space, you should use the rsync program instead). You could even automatically check your work into a version control system every so often; this works better with text than with binary files.
See Also
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