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    <title>simplicity -- duplicity made simple!</title>
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<h1>simplicity -- duplicity made simple!</h1>

<p><a href="">Simplicity</a> is a wrapper over <a href="">duplicity</a>.  Duplicity is a pretty
awesome backup tool for security conscious people, but it is somewhat
intimidating at first glance :-)</p>

<p><strong>QUICK START</strong>: if you have some idea of how duplicity works, and how it uses
encryption/gpg, etc., you can simply put simplicity somewhere in your <code>$PATH</code>
and run it without arguments to get going.</p>

<hr />

<li><a href="README.html">simplicity -- duplicity made simple!</a>
<li><a href="README.html#why-d">why duplicity</a>
<li><a href="README.html#caveats">caveats about duplicity</a></li>
<li><a href="README.html#why-s">why simplicity</a></li>
<li><a href="README.html#ops">simplicity operations</a>
<li>your first (full) backup</li>
<li>incremental backups</li>
<li>full backup again</li>
<li>checking things out and verifying the backup</li>
<li>restoring files</li>
<li><a href="README.html#incexc">include/exclude lists</a></li>

<hr />

<h2><a name="why-d"></a> why duplicity</h2>

<p>One word answer: paranoia ;-)</p>

<p>Duplicity is a backup tool that allows you to take encrypted backups on
untrusted media.  You can backup to a USB disk and not worry that someone can
simply read all your data from it if they find it.  You can backup to servers
where you have disk space but no real control, like Amazon's S3 service, or a
friend's hard disk (mutual backups are a good way to help each other out).
You can even use duplicity's "imap" backend to backup to an IMAP server like
gmail (note: I have not tried this!)</p>

<p>There are 3 options for encryption in duplicity.</p>

<li><p>The first option is to <strong>have your own gpg key</strong>.  If you want to make
unattended, encrypted, backups this is probably the best option.</p>

<p>If you don't already have a gpg key, start with <code>gpg --key-gen</code> and follow
the prompts.  This will create a secret and a public keypair in
<code>~/.gnupg</code>.  The prompts include one for a passphrase -- make sure you
choose one that is easy for you to remember even months later, yet hard
for anyone else to guess.</p>

<p>Once you start using this key to encrypt real backups, the contents of
your <code>$HOME/.gnupg</code> become very critical to <em>restoring</em> that data in the
future, so please save those files in multiple places.  (This is why a
good passphrase is needed).</p></li>
<li><p>The second option is to <strong>just type in a password everytime</strong> you do
something, without worrying about having to keep the contents of
<code>~/.gnupg</code> safe forever.  To make unattended, encrypted, backups like
this, you can set an environment variable (PASSPHRASE) to your password in
the backup script.  If you trust your local machine sufficiently and you
are the only user on it (as is typical on a desktop or laptop), this may
be a reasonable option.</p></li>
<li><p>The last option of course is not to use any encryption at all, which is
probably not such a great idea in general.  More to the point, if you're
not going to encrypt stuff you have a much wider choice of backup tools.
I'd recommend rdiff-backup -- still one of my favourites and has some nice
features that duplicity just cannot have -- or perhaps the up-and-coming
'bup' tool.</p></li>

<p>Duplicity takes a full backup the first time, and incremental backups
subsequently unless you force a full backup again.</p>

<p>For more details about duplicity see <a href="">this</a>.</p>

<h3><a name="caveats"></a> caveats about duplicity</h3>

<li><p>As someone said, <strong>mathematics cannot be bribed</strong>.  If you lose your gpg
keys, or forget your passphrase, your backup is toast.</p></li>
<li><p>Each full backup takes as much space as the first one -- even if no data
has changed.  This is good and bad -- good because it provides some
protection against partial disk corruption, and bad because it takes disk
space.  Depending on how much disk space you have, how much data you have
to backup, and how important it is, you have to decide how many full
backups too keep.</p>

<p>Personally, I keep between 2 and 4.  When I keep only 2, I backup to two
different machines.</p></li>
<li><p>if you delete <code>~/.cache/duplicity</code> (or some similar directory, depending
on how your distro sets it up), expect some pain next time you run
anything.  This is not duplicity's fault -- but it is something you need
to be aware of.</p></li>

<h2><a name="why-s"></a> why simplicity</h2>

<p>What part of "duplicity made simple" is not clear?  ;-)</p>

<p>Jokes apart, duplicity is quite complex and has a fairly dense man-page.
Simplicity sets up the basic stuff quickly and easily, to cover the most
common cases.</p>

<p>Notice that I don't deal with restoring data yet, but you can run duplicity
manually for that until I get around to adding it :-)</p>

<h2><a name="ops"></a> simplicity operations</h2>

<h3>your first (full) backup</h3>

<p>First, <strong>install</strong> simplicity by just copying it somewhere in your <code>$PATH</code>.</p>

<p>Then, run <code>simplicity edit</code> to create and edit the main config file.  The
format is very simple and the file comes with sample lines that you can
uncomment and change as needed.</p>

<p>Briefly, the "FILES" section specifies what files are to be backed up.  Each
files-spec looks like this:</p>

<pre><code>mymail  =   Maildir     mail-list

<p>'mymail' is the identifier that is used later in the conf file to refer to
this file-spec.  The files in 'Maildir' are to be backed up.  If the final
parameter exists, it is the name of a file that contains an include/exclude
list (see later for what this is and how it affects the backup).</p>

<p>The "DISKS" section specifies URLs for various remote storage areas that you
have access to.  See the duplicity man page for more on the syntax of the
"DISKS" part if the examples in the sample config do not suffice.  Each "disk"
is, as for FILES above, given an identifier for later use.</p>

<p>Similarly the "KEYS" section specifies the various gpg keys you may have and
the "OPTIONS" section allows you to specify any other duplicity options you

<p>Finally, the "NAMES" section is what ties all of these together.  Each "name"
entry looks like this:</p>

<pre><code>mail-to-usb =   mymail  seagate-500GB   sita

<p>So when you run <code>simplicity mail-to-usb</code>, you're backing up the files referred
to by 'mymail' (this means files from 'Maildir', optionally taking extra
include/exclude options from a supplied list), onto a 500 GB external disk
that you have designated 'seagate-500GB' in the "DISKS" section, encrypting
the backup with the gpg key referred to by 'sita' in the "KEYS" section.</p>

<p>The last argument can take some other values than a reference to a gpg key:
  * 'none' means no encryption
  * 'ask' means ask the user each time
  * 'env' means you will ensure the environment variable <code>PASSPHRASE</code> is
    somehow set before calling simplicity</p>

<p>Be patient; the first backup may take a lot more time than you expected,
though of course incremental backups go much, <em>much</em>, faster.</p>

<h3>incremental backups</h3>

<p>Incremental backups are done the same way: <code>simplicity mail-to-usb</code>, in this
example.  Duplicity ensures that all subsequent backups are incremental.</p>

<h3>full backup again</h3>

<p>Sadly, there is a penalty for running with incremental backups for too long --
a restore may take much longer.  Worse, the latest version may depend on more
and more files from previous backups, so if there is a disk failure, the
chances of losing backup data increase.</p>

<p>(Personally, I make a full backup every week.)</p>

<p>Let's say that, after reading about the disk space considerations in the
'caveats about duplicity' section above, you decided you want to keep 4 full
backups.  Simplicity makes this easy: <code>simplicity mail-to-usb full=4</code>.</p>

<p>But duplicity throws a wee little spanner in the works -- this cannot be done
unattended, unless you are putting the passphrase into the <code>PASSPHRASE</code> env
var :-(</p>

<p>So -- a truly unattended, fire and forget, backup is <em>only</em> possible if you
use the "env" method!  Run the backup normally via cron every day, and the
'full=4' operation on Sunday (for instance).</p>

<h3>checking things out and verifying the backup</h3>

<p>The 'status' operation (<code>simplicity mail-to-usb status</code>) runs duplicity's
'collection-status' command.  Similarly, 'list' runs 'list-current-files', and
'verify' runs 'verify'.</p>

<h3>restoring files</h3>

<p>Simplicity does not have code to restore -- that is usually best done manually
to avoid overwriting stuff!  Therefore, the single letter command 'r' will
print the actual restore command you should be using, except the filenames to
be restored and the destination directory.  Additionally, if you set the env
variable <code>FTR</code> to something, that will be prefilled as the file to restore.</p>

<h2><a name="incexc"></a> include/exclude lists</h2>

<p>This is a little more advanced, and for full details you should read the
duplicity man page.</p>

<p>Let's say you were backing up your email, which is in a directory
called 'Maildir'.  So the FILES section said:</p>

<pre><code>mymail      =   Maildir

<p>However, there are some sub-directories that you do not want backed up.  What
you do is, from the command line, run <code>simplicity edit mail-list</code>, which opens
up an editor.  Now enter these lines:</p>

<pre><code>- Maildir/.Trash
- Maildir/.Junk
- Maildir/.Drafts

<p>making sure that the "-" is at the first column and there is only one space
after it.</p>

<p>Now you again <code>simplicity edit</code> and change the 'mymail' line to</p>

<pre><code>mymail      =   Maildir     mail-list

<p>This tells simplicity to use the 'mail-list' file you created as an
include/exclude list while backing up 'Maildir'.</p>

<p>Include/exclude lists are very powerful; see the duplicity documentation for
more details.</p>

<p>Here's a more complex example.  In this case, I'm backing up an arbitrary set
of directories and files in my home directory.  So I put this in the FILES

<pre><code>myhome  =   .   home-list

<p>And then I <code>simplicity edit home-list</code> and add the following lines:</p>

<pre><code>- ./.thunderbird/default/*.slt/Cache
- ./.thunderbird/default/*.slt/ImapMail
- **

<p>In the previous example, you wanted almost everything in 'thundermail' except
the two trash directories/files.  By contrast, here you want almost nothing
out of the gazillions of files and directories that clutter a typical <code>$HOME</code>
today.  This is the reason you need that <code>- **</code> line at the end.</p>

<p>Also notice the exceptions within the thunderbird backup.  These lines must
come <em>before</em> the 3rd line.  To understand why, and more such nuances, please
read the documentation for duplicity.</p>

<hr />

<p>(c) Sitaram Chamarty,  Licensed under the GNU GPL v2.</p>
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