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+=====================================
+Shell-style configuration file parser
+=====================================
+
+libHX provides functions to read shell-style configuration files. Such files
+are common, for example, in ``/etc/sysconfig`` on Linux systems. The format is
+pretty basic; it only knows about ``key=value`` pairs and does not even have
+sections like INI files. Not relying on any features however makes them quite
+interchangable as the syntax is accepted by Unix Shells.
+
+Lines beginning with a hash mark (``#``) are ignored, as are empty lines and
+unrecognized keys.
+
+.. code-block:: sh
+
+	# Minimum / maximum values for automatic UID selection
+	UID_MIN=100
+	UID_MAX=65000
+
+	# Home directory base
+	HOME="/home"
+	#HOME="/export/home"
+
+Any form of variable or parameter substitution or expansion is highly
+implementation specific, and is not supported in libHX's reader. Even Shell
+users should not rely on it as you never know in which context the
+configuration files are evaluated. Still, you will have to escape specific
+sequences like you would need to in Shell. The use of single quotes is
+acceptable. That means::
+
+.. code-block:: sh
+
+	AMOUNT="US\$5"
+	AMOUNT='US$5'
+
+Synopsis
+========
+
+.. code-block:: c
+
+	#include <libHX/option.h>
+
+	int HX_shconfig(const char *file, const struct HXoption *table);
+	int HX_shconfig_pv(const char **path_vec, const char *file, const struct HXoption *table, unsigned int flags);
+	struct HXmap *HX_shconfig_map(const char *file);
+
+The shconfig parser reuses ``struct HXoption`` that fits very well in
+specifying name-pointer associations. ``HX_shconfig`` will read the given file
+using the key-to-pointer mappings from the table to store the variable
+contents. Of ``struct HXoption``, only the ``ln``, ``type`` and ``ptr`` fields
+are used. The list of accepted types is described in
+section [subsec:option-types].
+
+To parse a file, call ``HX_shconfig`` function with the corresponding
+parameters. If you want to read configuration files from different paths, i.e.
+to build up on default values, you can use ``HX_shconfig_pv``, which is a
+variant for reading a file from multiple locations. Its purpose is to
+facilitate reading system-wide settings which are then overriden by a file in
+the users home directory, for example (per-setting-override). It is also
+possible to do per-file-override, that is, a file in the home directory has
+higher precedence than a system-wide one in such a way that the system-wide
+configuration file is not even read. This is accomplished by traversing the
+paths in the “other” direction (actually you have to turn the array around) and
+stopping at the first existing file by use of the ``SHCONF_ONE`` flag.
+
+.. [#f2] pv = path vector
+
+``HX_shconfig_map`` will return all entries from the file in a HXmap, usable
+for parsing arbitrary keys without having to specify any static key table.
+
+``SHCONF_ONE``
+	Parsing files will stop after one file has been successfully parsed.
+	This allows for a “personal overrides system config” style.
+
+The call to ``HX_shconfig`` will either return >0 for success, 0 for no success
+(actually, this is never returned) and ``-errno`` for an error.
+
+Example
+=======
+
+Per-setting-override
+--------------------
+
+This example sources key-value pairs from a configuration file in a system
+location (``/etc``) first, before overriding specific keys with new values from the
+file in the home directory.
+
+.. code-block:: c
+
+	long uid_min, uid_max;
+	char *passwd_file;
+	struct HXoption options_table[] = {
+		{.ln = "UID_MIN",  .type = HXTYPE_LONG,   .ptr = &uid_min},
+		{.ln = "UID_MAX",  .type = HXTYPE_LONG,   .ptr = &uid_max},
+		{.ln = "PWD_FILE", .type = HXTYPE_STRING, .ptr = &passwd_file},
+		HXOPT_TABLEEND,
+	};
+	const char *home = getenv("HOME");
+	const char *paths[] = {"/etc", home, NULL};
+	HX_shconfig(paths, "test.cf", options_table, 0);
+
+Per-file-override
+-----------------
+
+This particular example reads from the file in the home directory first (if it
+exists), but stops after it has been successful, so any subsequent locations
+listed in the paths variable are not read. This has the effect that the file
+from the home directory has the highest priority too like in the previous
+example, but without any keys from the system files. Note the ``SHCONF_ONE``
+flag.
+
+.. code-block:: c
+
+	const char *home = getenv("HOME");
+	const char *paths[] = {home, "/usr/local/etc", "/etc", NULL};
+	HX_shconfig_pv(paths, "test.cf", options_table, SHCONF_ONE);