tag:blogger.com,1999:blog-49577428415157871982026-10-10T12:28:13.426+08:00Random thoughts on Linux, Java, security and other technical stuff...Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.comBlogger90125tag:blogger.com,1999:blog-4957742841515787198.post-42792696471273441132024-04-21T14:22:00.005+08:002024-04-21T14:25:49.304+08:00

Use the script below to set the min, max and CPU governor in Linux:#!/usr/bin/env bashMIN_FREQ=800000MAX_FREQ=1000000GOVERNOR=powersavefor i in `seq 0 3`;do  echo ${GOVERNOR} > /sys/devices/system/cpu/cpu${i}/cpufreq/scaling_governor  echo ${MAX_FREQ} > /sys/devices/system/cpu/cpu${i}/cpufreq/scaling_max_freq  echo ${MIN_FREQ} > /sys/devices/system/cpu/cpu${i}/cpufreq/

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com4tag:blogger.com,1999:blog-4957742841515787198.post-60813181922668731692021-06-09T20:59:00.006+08:002021-06-13T15:44:27.772+08:00

 OverviewThis article describes how to enable PAM authentication in Hive. By default, there's no authentication to Hive server. With PAM, authentication is performed against local OS user credentials.ProcedureStep 1 - JPam LibraryDownload latest copy JPam library from http://jpam.sourceforge.net/Latest version is 1.1 (JPam-Linux_amd64-1.1.tgz)Once downloaded, create /usr/hdp/ext/

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com4tag:blogger.com,1999:blog-4957742841515787198.post-48982676820749364802020-03-21T19:29:00.000+08:002020-03-21T19:29:02.933+08:00

If you encounter the following error running MCS: Internal error: CAL0009: Truncate table failed:  IDB-2009: Unable to perform the cpimport operation because 30084 with PID -1 is currently holding the table lock for session .   It's due to locks placed on the objects.  Use the following command to view locked objects in MCS: $ /usr/local/mariadb/columnstore/bin/

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com10tag:blogger.com,1999:blog-4957742841515787198.post-40582885734710480082017-03-09T19:07:00.001+08:002017-03-09T19:07:14.410+08:00

Script to create an external table in Hive to read records from a HDFS folder: CREATE EXTERNAL TABLE Mytable ( Id int, PlanID string, ServiceID string, SessionDuration int) STORED AS TEXTFILE ROW FORMAT DELIMITED FIELDS TERMINATED BY "," LOCATION "/user/hive/staging/" TBLPROPERTIES( "skip.header.line.count"="1" ); Using the script above, it'll use the files in /user/hive/

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com16tag:blogger.com,1999:blog-4957742841515787198.post-81828928596260861782016-08-23T14:09:00.001+08:002016-08-23T14:24:11.577+08:00

Before enabling authentication in MongoDB, we'll have to create a user and assign it a built-in role. We'll use the built-in "root" role that provides admin access to all databases. I've done this in Ubuntu using MongoDB 3.2. Issue the following commands to create a new user in the "admin" database: use admin db.createUser({ user: "admin", pwd: "password", roles: [ {

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com9tag:blogger.com,1999:blog-4957742841515787198.post-60749268206889146832016-08-07T00:00:00.003+08:002016-08-23T14:24:27.151+08:00

Here's a quick way to limit output of the grep command. Most of the time, we issue the following to find needle in the haystack: grep needle file.txt This prints out the matching pattern. If the output is way too long and we only need a section of it, we can use the extended grep (a.k.a. egrep) option. Here's how to use regular expressions to instruct grep to only display 40 characters

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com6tag:blogger.com,1999:blog-4957742841515787198.post-39425357403296637852016-07-27T10:52:00.000+08:002016-08-23T14:23:41.767+08:00

In my previous post, I've shown how to quickly create a WSDL/SOAP based web service. This post will build on top of that to include WS-Security. We'll be using simple username/password authentication. Add the following artifact into your Spring Boot pom.xml: org.apache.cxf cxf-rt-ws-security 3.1.6 We create a callback handler class to perform our custom authentication. This

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com10tag:blogger.com,1999:blog-4957742841515787198.post-46064464682325325812016-07-22T21:21:00.000+08:002016-08-23T14:25:23.059+08:00

My previous post shows how we can easily create a SOAP based web service using Spring Boot, CXF, JAX-WS and JAXB. There's a small matter to note when naming functions. The following function naming works: package com.techtots.services; import javax.jws.WebMethod; import javax.jws.WebParam; import javax.jws.WebResult; import javax.jws.WebService; import javax.xml.bind.annotation.XmlElement;

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com7tag:blogger.com,1999:blog-4957742841515787198.post-77830813414696960672016-07-22T21:09:00.001+08:002016-08-23T14:25:38.297+08:00

Here's a quick way to use Spring Boot to expose web services via WSDL/SOAP using CXF, JAX-WS and JAXB. Add the following artifacts into your Spring Boot pom.xml: org.apache.cxf cxf-rt-frontend-jaxws 3.1.6 org.apache.cxf cxf-rt-transports-http 3.1.6 We start off by creating the request and response classes. These classes act as the value objects for the

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com4tag:blogger.com,1999:blog-4957742841515787198.post-32233090344905247202014-07-26T14:39:00.000+08:002014-08-05T17:41:15.385+08:00

Here's what I did to configure Apache to return the proper CORS headers for my webapp consumption which is written in AngularJS: Header always set Access-Control-Allow-Origin "*" Header always set Access-Control-Allow-Methods "GET, POST, OPTIONS" Header always set Access-Control-Allow-Headers "accept, content-type" Header always set Access-Control-Allow-Credentials "true" That can be set in the

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com7tag:blogger.com,1999:blog-4957742841515787198.post-11173059626623406332014-02-11T15:28:00.001+08:002014-02-11T15:29:16.796+08:00

Here's a quick way to resize images via shell using mogrify. It's part of ImageMagick package. mogrify -resize 60% *.jpg This will resize all files ending with .jpg extension to 60% of their original size. We're only scratching the surface of what mogrify can do. Have fun exploring :)

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-17844560601092202952014-02-03T10:01:00.000+08:002014-02-03T10:01:15.580+08:00

Here's a neat way to set some default parameter values in a PHP function. This only works if a function param is passed in as associative array. function create_profile($values) { if (!is_array($values)) { $values = array(); } // Default key/values $values += array( 'uid' => NULL, 'username' => '', 'mobile' => '99999999', 'location' => 'POINT(0 0)',

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com1tag:blogger.com,1999:blog-4957742841515787198.post-46974534393286359312014-01-28T21:59:00.001+08:002014-01-28T21:59:54.692+08:00

Here's a quick way on how to use HTML5 placeholder attribute in Drupal forms. Example below is altering the login form in a custom theme: function mytheme_form_alter(&$form, &$form_state, $form_id) { if ($form_id == 'user_login') { $form['name']['#attributes'] = array('placeholder' => $form['name']['#title']); $form['pass']['#attributes'] = array('placeholder' => $form['pass']['#

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-63273440247929784312013-09-11T20:03:00.000+08:002013-09-11T20:03:13.436+08:00

Here's how to use JMeter's Regular Expression Extractor post-processor to extract the response from a HTTP Request sampler and use it in the subsequent request. In the screen above, I'm extracting the value of the hidden form element named "t".  If there's no match to the regular expression, the default value "NO TOKEN" will be returned. To use the extracted value in subsequent HTTP

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-8856479108457189492013-08-15T01:46:00.000+08:002013-08-15T01:46:09.575+08:00

This is a short post on how to use Drupal's hook_theme() to customize a layout within your own custom module. Start off with implementing the hook_theme() function in your module: /** * Implements hook_theme() * @param type $existing * @param type $type * @param type $theme * @param type $path * @return array */ function mypm_theme($existing, $type, $theme, $path) { $themes = array(

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-5380475805786669602013-08-14T21:17:00.000+08:002013-08-14T21:25:09.276+08:00

Last part of the article is to use either Hibernate or Spring's JdbcTemplate to retrieve data. The following class is the BaseDao where DataSource and Hibernate SessionFactory are injected and used by concrete DAO classes: package com.techtots.services.api.dao; import javax.sql.DataSource; import org.hibernate.SessionFactory; import org.springframework.beans.factory.annotation.Autowired;

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-55011657710593747842013-08-14T20:56:00.004+08:002013-08-14T21:18:01.652+08:00

Second part of the article will focus on the controllers which will process clients' requests as well as other helper classes. We start off with a custom exception. We add on a HttpStatus code into the exception to return to clients: package com.techtots.services.api.common.exceptions; import org.springframework.http.HttpStatus; public class RestException extends Exception { private static

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-87358150625629505992013-08-14T19:36:00.000+08:002013-08-14T19:36:44.560+08:00

This is post serves as a reference point to quickly setup a Java web application with Spring 3 MVC, Hibernate 4, JdbcTemplate and a partial REST controller. We'll be consuming and responding JSON content via the REST controllers. I'm using Eclipse as the IDE and will be connecting to MySQL database. Let's start off with the libraries: antlr-2.7.7.jar aopalliance.jar bonecp-0.7.1.RELEASE.jar

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com1tag:blogger.com,1999:blog-4957742841515787198.post-7297060370153550502013-08-01T20:47:00.000+08:002013-08-01T20:47:12.606+08:00

Here are 2 things to do right after meeting all requirements dictated by Kohana's install script: Set Cookie::$salt value in application/bootstrap.php: Cookie::$salt = 'my*salt*value*'; Change base_url value in application/bootstrap.php to match the server configuration: Kohana::init(array( 'base_url' => '/my_app/', )); In this example, you should be calling http://myserver.com/my_app/

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-32928324190985226922013-07-31T12:07:00.000+08:002013-07-31T12:07:43.950+08:00

The Java MessageFormat class allows user to pre-define a string with placeholders and then fill the placeholders with actual strings later to construct a proper message. It's all fine if you're used to numbered placeholders e.g. {0} and {1}. Since I'm used to Drupal's format_string() function, here's a better alternative. Apache Commons has a StrSubstitutor class which allows use of named

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com4tag:blogger.com,1999:blog-4957742841515787198.post-50822757801785431842013-07-30T21:53:00.001+08:002013-07-30T21:53:24.238+08:00

Here's how to use Drupal's db_select function to perform a SQL UNION like below: select uid from users where type = 'i' union select uid from users_archive where type = 'i' Bad example, but I can't think of a proper example now :) Drupal db_select version: $q1 = db_select('users', 'u') ->fields('u', array('uid')) ->condition('type', 'i'); $q2 = db_select('users_archive', 'ua')

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-7218710905799360032013-07-26T10:31:00.001+08:002013-07-26T10:31:56.826+08:00

Here's a convenient way to obtain the last executed SQL query when using CodeIgniter's database class. Code snippet for this example: $this->db->select('status'); $this->db->from('tbl_user'); $this->db->where('user_id', $user_id); $results = $this->db->get(); echo $this->db->last_query(); The last call to last_query() will output the actual SQL executed.

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-13861247261166674112013-07-17T08:59:00.000+08:002013-07-17T08:59:35.101+08:00

Here's how to use Drupal's db_select function to perform a SQL INNER JOIN like below: SELECT n.*, u.name FROM node n INNER JOIN users u on n.uid = u.uid WHERE u.id = 3 Drupal db_select version: $q = db_select('node', 'n'); $q->join('users', 'u', 'u.uid = n.uid'); $q->fields('n'); $q->fields('u', array('name')); $q->condition('u.uid', 3); $results = $q->execute();

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-44944419330424985192013-07-15T21:40:00.001+08:002013-07-15T21:40:33.524+08:00

Here's a quick way (although not the best one) to stream an Excel file generated by JExcelAPI (http://jexcelapi.sourceforge.net/). I'm using the servlet output stream in this case. HttpServletResponse response = getContext().getResponse(); ServletOutputStream sos = response.getOutputStream(); WritableWorkbook workbook = Workbook.createWorkbook(sos); WritableSheet sheet =

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com0tag:blogger.com,1999:blog-4957742841515787198.post-42282094807312569902013-07-01T21:39:00.001+08:002013-07-17T19:20:13.563+08:00

Drupal stores date/time value as int columns in MySQL. Its value is UNIX timestamp based. You will not be able to determine the actual date/time by selecting from the table. Here's a convenient way to convert the date/time columns directly from SQL: SELECT cid, data, FROM_UNIXTIME(created) FROM main_cache You can also use this in the WHERE clause like below: SELECT COUNT( * ) FROM

Mikehttp://www.blogger.com/profile/12828408134779227322noreply@blogger.com1