The configuration file is line-oriented.
Blank lines and whitespace at the beginning and end of a line are ignored.
Comments start with ``#`` or ``%`` in the first column
(after any beginning-of-line whitespace) and go to the end of the line.

The file is split into sections.
Every section begins with “[SECTIONNAME]” and
contains a number of options of the form “OPTION=VALUE”.
There may be whitespace around the ``=`` (equal sign).
Section names and options are *case-insensitive*.

The values, however, are *case-sensitive*.
In particular, boolean values are one of ``YES`` or ``NO``.
Values can include whitespace by surrounding
the entire value with ``"`` (double quote).
Note, however, that there are no escape characters in such strings;
all characters between the double quotes (including other double quotes)
are taken verbatim.

Values that represent filenames can begin with a ``/bin/sh``-like
variable reference.
This can be simple, such as ``$TMPDIR/foo``, or complex,
such as ``${TMPDIR:-${TMP:-/tmp}}/foo``.
See ``[PATHS]`` (below).

Values that represent a time duration are represented as a series
of one or more ``NUMBER UNIT`` pairs, e.g. ``60 s``, ``4 weeks 1 day``,
``5 years 2 minutes``.

Values that represent an amount are in the usual amount syntax:
``CURRENCY:VALUE.FRACTION``, e.g. ``EUR:1.50``.
The ``FRACTION`` portion may extend up to 8 places.


The “[PATHS]” section is special in that it contains paths that can be
referenced using “$” in other configuration values that specify
*filenames*. Note that configuration options that are not specifically
retrieved by the application as *filenames* will not see “$”-expressions
expanded. To expand “$”-expressions when using ``taler-config``, you must pass
the ``-f`` command-line option.

The system automatically pre-populates the “[PATHS]” section with a few values
at run-time in addition to the values that are in the actual configuration
file.  These automatically generated values refer to installation properties
from `GNU autoconf
<https://www.gnu.org/prep/standards/html_node/Directory-Variables.html>`_. The
values are usually dependent on an ``INSTALL_PREFIX`` which is determined by
the ``--prefix`` option given to configure.  The canonical values are:

  * LIBEXECDIR = $INSTALL_PREFIX/taler/libexec/
  * DOCDIR = $INSTALL_PREFIX/share/doc/taler/
  * ICONDIR = $INSTALL_PREFIX/share/icons/
  * LOCALEDIR = $INSTALL_PREFIX/share/locale/
  * PREFIX = $INSTALL_PREFIX/
  * BINDIR = $INSTALL_PREFIX/bin/
  * LIBDIR = $INSTALL_PREFIX/lib/taler/
  * DATADIR = $INSTALL_PREFIX/share/taler/

Note that on some platforms, the given paths may differ depending
on how the system was compiled or installed, the above are just the
canonical locations of the various resources.