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  /dev/null and /dev/tty in Linux

In Linux, there are two special files /dev/null and /dev/tty. /dev/null will drop all the data written to it, i.e, when program writes data to this file, it means the program has completed the data write operation. But in  fact it does nothing, if you just want the status of a command but not the output of a command, this feature will be very useful. See below shell codes:     /> vi test_dev_null.sh        #!/bin/bash    if grep...

   Linux,/dev/null,/dev/tty     2013-03-04 02:23:23

  Big Corporate Layoffs Hit Shenzhen IT Manufacturing Business

At 11:00 on March 29, 3 employees were ready to jump from Shenzhen Foxconn's longhua building G14. According to witnesses, those 3 employees were negotiating with company regarding the “Foxconn diversion plan”. Liu Kun, Foxconn public speaker, told reporters that many employees are working negatively to resist this plan, but Foxconn does not agree or support their actions in this way. " Company like Foxconn with large-scale labor-intensive manufacturing enterprises in Shenzhen, is f...

   Layoff,Career,China     2013-04-01 06:44:43

  Why cannot compare double values directly for equality?

A question in PHP: Get some value from the database and use floatval() to convert it to floatint point value, then compare it with another value which is also converted to floating point value with floatval(). These two values are the same when using var_dump() to output, the two outputs are float(8.87), they are the same. But when comparing them for equality, the result is weird., they are not equal. Why?To analyze this question, we need to start with PHP data types. PHP uses weak types. In PHP...

   PHP,floating, precision,compare,equality     2012-06-27 09:01:36

  How to choose JavaScript template engine?

With the increase of density of web front end development, AJAX and JSON are used more and more frequently, it's necessary to use many tags in front end development. You may have a JSON object as below: var data={  email: 'terry.li@gbin1.com,  gender: 'male'  } Then you need to organize the JSON data into page elements. var email, gender;email= ' ' + data.email+ '; gender= ' ' + data.gender + '; $('#contentwrapper‘).append(content).append(gender); The output is very simple: ...

   JavaScript template engine,Template     2012-10-07 07:03:58

  What is pjax and why we should use it?

What is pjax? Now many websites such as Facebook, Twitter support one browsing style which is when you click one link on their sites, the page will not be redirected, instead only the page contents are updated and URL on address bar is changed. This kind of user experience is much better compared to load the whole page with a blink. There is one important component in the above browsing experience, these websites' AJAX refresh support browser history, when refreshing the page, the address on the...

   pjax,AJAX,history     2013-04-23 12:22:37

  12 useful Chrome commands

Many useful features of Chrome don't show up on its menus. You can access them through the chrome:// command. In this article we will introduce 12 useful chrome:// commands. 1. chrome://flags It can be used to turn on or turn off some chrome features. 2. chrome://dns This command will show the domain name list caught by the browser. 3. chrome://downloads You can access this through chrome menu as well. The shortcut is Ctrl+J 4. chrome://extensions This command equals to Menu->Tools->Ext...

   Chrome,chrome://     2013-01-25 04:38:03

  How does MySQL handle DROP TABLE

A few days ago, when executing DROP TABLE in MySQL, all processes including DDL and DML were hung until DROP TABLE was completed. I am confused about this phenomenon. I have reviewed the source codes of MySQL to check how MySQL internally handle DROP TABLE. When user trigger DROP TABLE command: ########################MySQL SERVER drop table######################## /* Sql_table.cc  delete (drop) tables. */bool mysql_rm_table( )   /*   Execute the drop of a normal or temporary...

   MySQL,DROP TABLE     2012-09-24 11:34:05

  PHP advisory file lock : flock

When we process a file in PHP, we may often need to acquire a lock so that other scripts cannot edit the same file at the same time. There is a flock() function in PHP which can help us lock the file we want to process. But there is one issue we should take care. Recently, ffb encountered one issue while he was trying to lock a file handle. The codes are below: $filename = "/tmp/lock.txt";      $fp = fopen($filename, "r+");   if (!$fp...

   flock(),advisory locking,PHP     2013-04-23 11:42:48

  â€œExperience says it all”- Pentaho ETL Developers’ Comment on the Use of ETL Tools

Since months Pentaho ETL developers have been juggling with three distinct tools- Pentaho DI, SSIS, and PowerShell. Their experience has provided them new perspective on the cons and pros of every tool. In this post, they are sharing their experience with these tools and explain their significance. Before getting started, they first would like to explain ETL in brief and how the tools suits ETL landscape. ETL is Extract Transform Load. Informatica was the initial ETL tool introduced in the mid n...

   Pentaho BI ETL tools     2015-05-13 01:14:57

  10gen provides free training courses for MongoDB

MongoDB is an open source document oriented database, developed with C++, it is to solve some real problems existing among development communities. In October 2007, MongoDB development began at 10gen, in 2009, MongoDB was open sourced as a standalone product. 10gen provides technical support, training and consultancy service. According to 10gen education, 10gen will provide some training courses for MongoDB starting from 22 October, 2012. Now it's available for registration. There are two cours...

   MongoDB,10gen,training,course,free     2012-09-20 22:51:43

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