INSTALLATION:

Thank you for trying duplicity.  To install, run:

        python setup.py install

The build process can be also be run separately:

        python setup.py build

The default prefix is /usr, so files are put in /usr/bin,
/usr/share/man/, etc.  An alternate prefix can be specified using the
--prefix=<prefix> option.  For example:

        python setup.py install --prefix=/usr/local
        export PYTHONPATH='/usr/local/lib/python.x/site-packages/'
        /usr/local/bin/duplicity -V


REQUIREMENTS:

 * Python 2.7, 3.6, 3.7
 * librsync v0.9.6 or later
 * GnuPG for encryption
 * fasteners 0.14.1 or later for concurrency locking
 * for scp/sftp -- python-paramiko
 * for ftp -- lftp version 3.7.15 or later
 * Boto 2.0 or later for single-processing S3 or GCS access (default)
 * Boto 2.1.1 or later for multi-processing S3 access
 * Boto 2.7.0 or later for Glacier S3 access

If you install from the source package, you will also need:

 * Python development files, normally found in module 'python-dev'.
 * librsync development files, normally found in module 'librsync-dev'.


A NOTE ON GnuPGInterface.py AND MULTIPLE GPG PROCESSES:

GnuPGInterface is used to access GPG from duplicity.  The original
works quite well and has no bugs, however, we have patched the one
used in duplicity.  Why?  Duplicity is not perfect, yet, and has a
problem when handling long chains of incremental backup or restore
operations.  The problem is that the waitpid() call only happens
after all the iterations complete, and with a long chain, that can
be a long while.  Unless the waitpid() call is made, the child process
remains active.  Duplicity's GnuPGInterface is patched to start an
immediate threaded waitpid() for each GPG task, thus harvesting the
task and freeing it's resources in a timely manner.  This does not
affect the operation of duplicity, merely frees resources on time.

Why the note?  Some package maintainers remove duplicity's GnuPGInterface
in error, obviously unknowing of this issue and patch duplicity to use
the old unmaintained unpatched GnuPGInterface interface again.
So, if you have the problem that lots of GPG tasks are hanging around,
check and see if this has been done in your distro, and if so, report this
matter as a bug to the distro or package maintainer.

As of october 2012 we pull the handbrake and refactor our code and rename
the class to gpginterface in the hope that package maintainers will stumble
over it and stop this problematic behaviour for good.

DEVELOPMENT

For more information on downloading duplicity's source code from the
code repository and developing for duplicity, see README-REPO.

HELP:

For more information see the duplicity home page at:

  http://www.nongnu.org/duplicity

or post to the mailing list at

  http://mail.nongnu.org/mailman/listinfo/duplicity-talk/
