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diff --git a/frags/common-conf-syntax.rst b/frags/common-conf-syntax.rst new file mode 100644 index 00000000..2ca15058 --- /dev/null +++ b/frags/common-conf-syntax.rst @@ -0,0 +1,61 @@ +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 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. + +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:-${TMP:-/tmp}}/foo``. The variables are expanded either using +key-values from the ``[PATHS]`` section (see below) or from the environment +(``getenv()``). The values from ``[PATHS]`` take precedence over those from +the environment. If the variable name is found in neither ``[PATHS]`` nor the +environment, a warning is printed and the value is left unchanged. Variables (including those from the environment) are expanded recursively, so if ``FOO=$BAR`` and ``BAR=buzz`` then the result is ``FOO=buzz``. Recursion is bounded to at most 128 levels to avoid undefined behavior for mutually recursive expansions like if ``BAR=$FOO`` in the example above. + +The ``[PATHS]`` section is special in that it contains paths that can be +referenced using ``$`` 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 and automatically overwriting those values if they are present). +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. These +automatically generated values are never written to disk. |