From 96048c4fd067f5b8b034b8fbc0566c4422f7c2c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=BD=90?= <48374300+wulnm@users.noreply.github.com>
Date: Sun, 13 Jun 2021 20:14:14 +0800
Subject: [PATCH] add string expression explanation
MIME-Version: 1.0
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添加了一些表达式说明以及对齐注释
---
 docs/operating-system/Shell.md | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/docs/operating-system/Shell.md b/docs/operating-system/Shell.md
index 53466d11..c4d4d43a 100644
--- a/docs/operating-system/Shell.md
+++ b/docs/operating-system/Shell.md
@@ -235,12 +235,16 @@ echo ${str:0:10} #输出:SnailClimb
 #author:amau
 
 var="https://www.runoob.com/linux/linux-shell-variable.html"
-
-s1=${var%%t*}#h
-s2=${var%t*}#https://www.runoob.com/linux/linux-shell-variable.h
-s3=${var%%.*}#http://www
-s4=${var#*/}#/www.runoob.com/linux/linux-shell-variable.html
-s5=${var##*/}#linux-shell-variable.html
+# %表示删除从后匹配, 最短结果
+# %%表示删除从后匹配, 最长匹配结果
+# #表示删除从头匹配, 最短结果
+# ##表示删除从头匹配, 最长匹配结果
+# 注: *为通配符, 意为匹配任意数量的任意字符
+s1=${var%%t*} #h
+s2=${var%t*}  #https://www.runoob.com/linux/linux-shell-variable.h
+s3=${var%%.*} #http://www
+s4=${var#*/}  #/www.runoob.com/linux/linux-shell-variable.html
+s5=${var##*/} #linux-shell-variable.html
 ```
 
 ### Shell 数组