Organize files into categorized directories

Renamed and moved files into categorized directories for better organization. Categories include Shell-Programming, File-IO, Process-Control, and Signal-and-Piping.

1_Shell-Programming/check_grade.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# 清空输出文件
+>record2
+# 从 record 文件中读取每一行记录
+while read name ch math eng; do
+    # 判断三个科目中是否有不及格（成绩低于 60）
+    if [ "$ch" -lt 60 ] || [ "$math" -lt 60 ] || [ "$eng" -lt 60 ]; then
+        echo "$name $ch $math $eng" >>record2
+    fi
+done <record