diff --git a/shell/shell变量提取赋值.md b/shell/shell变量提取赋值.md
index 18c3e60..00762d6 100644
--- a/shell/shell变量提取赋值.md
+++ b/shell/shell变量提取赋值.md
@@ -1,3 +1,4 @@
+
 |--|--|
 |表达式|含义|
 |${var:-aa}|若var为空或未设定, 返回aa, var值不变|