From 41843856d1f09c8fe718630a6fa4318441c7be38 Mon Sep 17 00:00:00 2001 From: Evan Goode Date: Mon, 16 Oct 2023 18:44:53 +0000 Subject: [PATCH 04/11] Document shell-like parameter expansion for variables =changelog= msg: Support ${parameter:-word} and ${parameter:+word} parameter expansion in variables type: enhancement resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1789346 --- doc/conf_ref.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/doc/conf_ref.rst b/doc/conf_ref.rst index 9397f0008..fdb34323c 100644 --- a/doc/conf_ref.rst +++ b/doc/conf_ref.rst @@ -829,6 +829,18 @@ Although users are encouraged to use named variables, the numbered environmental [myrepo] baseurl=https://example.site/pub/fedora/$DNF1/releases/$releasever +A limited form of shell-like parameter expansion is supported for variables. + +``${my_variable:-word}`` If ``my_variable`` is unset or empty, then ``word`` will be substituted. Otherwise, the value of ``my_variable`` will be substituted. + +``${my_variable:+word}`` If ``my_variable`` is set and not empty, then ``word`` will be substituted. Otherwise, the empty string will be substituted. + +Parameter expansions can be nested up to a maximum depth of 32. For example:: + + ${my_defined_variable:+${my_undefined_variable:-foobar}} + +will evaluate to ``foobar``. + .. _conf_main_and_repo_options-label: -- 2.49.0