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-rw-r--r--DOCS/man/en/input.rst18
1 files changed, 15 insertions, 3 deletions
diff --git a/DOCS/man/en/input.rst b/DOCS/man/en/input.rst
index e40457e099..362e8a4cf8 100644
--- a/DOCS/man/en/input.rst
+++ b/DOCS/man/en/input.rst
@@ -509,15 +509,27 @@ The following expansions are supported:
fails, expand to an error string. (Use ``${NAME:}`` with a trailing
``:`` to expand to an empty string instead.)
If ``NAME`` is prefixed with ``=``, expand to the raw value of the property
- (see below).
+ (see section below).
``${NAME:STR}``
Expands to the value of the property ``NAME``, or ``STR`` if the
property cannot be retrieved. ``STR`` is expanded recursively.
+``${?NAME:STR}``
+ Expands to ``STR`` (recursively) if the property ``NAME`` is available.
``${!NAME:STR}``
Expands to ``STR`` (recursively) if the property ``NAME`` cannot be
retrieved.
-``${?NAME:STR}``
- Expands to ``STR`` (recursively) if the property ``NAME`` is available.
+``${?NAME==VALUE:STR}``
+ Expands to ``STR`` (recursively) if the property ``NAME`` expands to a
+ string equal to ``VALUE``. You can prefix ``NAME`` with ``=`` in order to
+ compare the raw value of a property (see section below). If the property
+ is unavailable, or other errors happen when retrieving it, the value is
+ never considered equal.
+ Note that ``VALUE`` can't contain any of the characters ``:`` or ``}``.
+ Also, it is possible that escaping with ``"`` or ``%`` might be added in
+ the future, should the need arise.
+``${!NAME==VALUE:STR}``
+ Same as with the ``?`` variant, but ``STR`` is expanded if the value is
+ not equal. (Using the same semantics as with ``?``.)
``$$``
Expands to ``$``.
``$}``