GNU Taler merchant has these additional dependencies:

- libqrencode >= 4.0.0

The following steps assume all dependencies are installed.

First, unpack the GNU Taler merchant tarball and change into
the resulting directory.
Then, use the following commands to build and install the merchant backend:

.. code-block:: console

     $ ./configure [--prefix=PFX] \
                   [--with-gnunet=GNUNETPFX] \
                   [--with-exchange=EXCHANGEPFX]
     $ # Each dependency can be fetched from non standard locations via
     $ # the '--with-<LIBNAME>' option. See './configure --help'.
     $ make
     # make install

If you did not specify a prefix, the exchange will install to
``/usr/local``, which requires you to run the last step as ``root``.

You have to specify ``--with-exchange=/usr/local`` and/or
``--with-gnunet=/usr/local`` if you installed the exchange and/or
GNUnet to ``/usr/local`` in the previous steps.

Depending on the prefixes you specified for the installation and the
distribution you are using, you may have to edit ``/etc/ld.so.conf``, adding
lines for ``GNUNETPFX/lib/`` and ``EXCHANGEPFX/lib/`` and ``PFX/lib/``
(replace the prefixes with the actual paths you used). Afterwards, you should
run ``ldconfig``. Without this step, it is possible that the linker may not
find the installed libraries and launching the Taler merchant backend would
then fail.
