From 98d438b497e1f2da1776367825552910b1a52bcc Mon Sep 17 00:00:00 2001
From: Egor Tensin <Egor.Tensin@gmail.com>
Date: Tue, 22 Nov 2016 03:08:59 +0300
Subject: bash.md: how to declare arrays

---
 bash.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/bash.md b/bash.md
index 628bfa8..6f729a0 100644
--- a/bash.md
+++ b/bash.md
@@ -4,6 +4,26 @@ GNU `bash`
 (Associative) arrays
 --------------------
 
+### Declaration
+
+`"${#xs[@]}"` doesn't work with `nounset` if `xs` wasn't defined, i.e. was
+declared with either of
+
+    local -a xs
+    declare -a xs
+    local -A xs
+    declare -A xs
+
+Therefore, if you want to extract the length of an array, append `=()` to the
+statements above.
+
+    local -a xs=()
+    declare -a xs=()
+    ...
+
+And now `"${#xs[@]}"` works with `nounset`.
+It doesn't affect expansion (see below) though.
+
 ### Expansion
 
 #### Do
-- 
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