[Ubuntu 常見問題] Syntax error: Bad for loop variable解決方法

轉載自 這裡 
前言 : 
今天接手一個 Test automation 的 shell script, 無奈怎麼跑都會出現 "Bad for loop variable". 查了一下發現原有的 script 語法並沒有錯誤. 還好有 google 到原來是 Ubuntu 使用 dash 取代了我們常見的 bash. 而在 for loop 地方會出現如下報錯訊息 : 

john@tda-server:~/Test/CreateAccount$ sudo ./creataccount.sh <執行 script>
./creataccount.sh: 8: Syntax error: Bad for loop variable

而第八行的部分剛好就是 for loop : 

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1. #!/bin/sh  
2. loop=755  
3. touch passwdlist.txt  
4.   
5.   
6. ## Create account and prepare password list file  
7.   
8. for (( i=1; i<=${loop}; i+=1 ))  
9. #for ((i=756;i<=777;i+=1));  
10. do  
11.         echo -n "*** $i ***  "  
12.         useradd -m user$i  
13.         echo user$i":"user$i >> passwdlist.txt  
14.         echo "process next account..."  
15. done  
16.   
17.   
18. echo "Change password..."  
19. ## Start to create account  
20. cat passwdlist.txt | chpasswd  

解決方法 : 
解決方法就是執行下面命令 : 

john@tda-server:~/Test/CreateAccount$ sudo dpkg-reconfigure dash

接著會出現下面的對話框, 按Tab 選擇 後退出 : 
 

再次執行 shell script 便可以成功! 

補充說明 : 
* 鳥哥Linux 私房菜 - 第十三章、學習 Shell Scripts

[ Java 代碼範本 ] 使用 Java 操作 SQLiteJDBC

前言 : 
這裡的範例代碼是基於 Xerial SQLite JDBC Driver 進行實現. 底下是官網對於該 SQLite JDBC Driver 的說明 : 

Our SQLiteJDBC library, developed as a part of Xerial project, requires no configuration since all native libraries for Windows, Mac OS X, Linux and pure-java SQLite, which works in any OS enviroment, are assembled into a single JAR (Java Archive) file. The usage is quite simple; Download our sqlite-jdbc library, then append the library (JAR file) to your class path. See the sample code.

範例代碼 : 

- Sample.java :

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1. import java.sql.Connection;  
2. import java.sql.DriverManager;  
3. import java.sql.ResultSet;  
4. import java.sql.SQLException;  
5. import java.sql.Statement;  
6.   
7.   
8. public class Sample  
9. {  
10.   public static void main(String[] args) throws ClassNotFoundException  
11.   {  
12.     // load the sqlite-JDBC driver using the current class loader  
13.     Class.forName("org.sqlite.JDBC");  
14.       
15.     Connection connection = null;  
16.     try  
17.     {  
18.       // create a database connection  
19.       connection = DriverManager.getConnection("jdbc:sqlite:sample.db");  
20.       Statement statement = connection.createStatement();  
21.       statement.setQueryTimeout(30);  // set timeout to 30 sec.  
22.         
23.       statement.executeUpdate("drop table if exists person");  
24.       statement.executeUpdate("create table person (id integer, name string)");  
25.       statement.executeUpdate("insert into person values(1, 'leo')");  
26.       statement.executeUpdate("insert into person values(2, 'yui')");  
27.       ResultSet rs = statement.executeQuery("select * from person");  
28.       while(rs.next())  
29.       {  
30.         // read the result set  
31.         System.out.println("name = " + rs.getString("name"));  
32.         System.out.println("id = " + rs.getInt("id"));  
33.       }  
34.     }  
35.     catch(SQLException e)  
36.     {  
37.       // if the error message is "out of memory",   
38.       // it probably means no database file is found  
39.       System.err.println(e.getMessage());  
40.     }  
41.     finally  
42.     {  
43.       try  
44.       {  
45.         if(connection != null)  
46.           connection.close();  
47.       }  
48.       catch(SQLException e)  
49.       {  
50.         // connection close failed.  
51.         System.err.println(e);  
52.       }  
53.     }  
54.   }  
55. }  

至於如何指定 DB 檔案的位置, 是透過 DriverManager.getConnection() 呼叫時同時指定, 幾個簡單範例如下 : 
* Here is an example to select a file C:\work\mydatabase.db (in Windows) 

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1. Connection connection = DriverManager.getConnection("jdbc:sqlite:C:/work/mydatabase.db");  

* A UNIX (Linux, Mac OS X, etc) file /home/leo/work/mydatabase.db 

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1. Connection connection = DriverManager.getConnection("jdbc:sqlite:/home/leo/work/mydatabase.db");  

補充說明 : 
* Free學習札記 : SQLite with Java 
* Java Gossip: Statement、 ResultSet