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  Create temp file in Bash using mktemp and trap

When working on Linux Bash, sometimes there is need to create temporary file. A common way of creating temp file on Linux is creating some file in /tmp directory. However there is security risk when creating temp file in /tmp directory. This post will show how to securely create temp file in Linux Bash. When creating file in /tmp directory, there are some security risks. This directory can be accessed by any user on the system, any user can write data into this directory as well. The files creat...

   LINUX,MKTEMP,TRAP,TEMP FILE     2019-12-30 23:28:23

  A completely new approach to surveillance - should you be worried?

Paranoia is not necessarily a bad thing - assuming someone is really out there to get you. True or not, the paranoid have had issues they need to control explode as the internet developed, they also got specific tools to make their secrets (or their life, not everybody has a dark secret) more secure and under control. Unfortunately to them, and to the amazement of science and science fiction fans worldwide, a new way of obtaining secrets has appeared and it’s something very few expected. ...

   security     2014-08-11 05:41:58

  Why does Symbian collapse?

On 24th January, Nokia announces a disappointing news that they would give up Symbian. The 808 PureView released last year will be its last Symbian model.  Symbian was born in 1998, it was supported by the then three mobile giants : Sony Ericson, Motorola and Nokia after its birth, later Samsung and LG also joined the Symbian camp. In 2000, the first Symbian model in the world Ericoson R380 was released, in 20006, there were over 100 million Symbian handphones on the market. But in 2007, t...

   Nokia, Symbian, Collapse, Analysis     2013-01-28 03:06:09

  All I Know About Certificates -- Websites

In last article, we know the role of clients and their responsibilities for certificate verification. Finally, let's talk about websites. We've discussed many potential issues between CAs and clients concerning certificates, but the most frequent issue is with websites—many websites have faced this problem: certificate expiration. Websites need to ensure two things: Ensure their certificate does not expire. Protect their private key from being leaked. If someone else obtains the priv...

   CLIENTS,WEBSITES,SSL CERTIFICATE,CERTIFICATE AUTHORITY,CA     2024-07-26 22:33:29

  Many Chinese applicants to US universities may be affected by Gmail cut out

Just after Christmas, many Chinese found that they could not connect to Gmail anymore in mainland China. Since Google announced leaving from China in 2010, the web version of Gmail was not accessible anymore. But people from China could still access Gmail through some Gmap apps. This time, Gmail is not accessible even with these apps. It is said that all the mail service protocols of Gmail including IMAP/POP/SMTP have been cut out by Chinese government. This means no mails can be sent to or rece...

   Gmail, China, Gmail cut out     2014-12-30 00:35:28

  jsonSerialize() in extended class

Since PHP 5.4.0, there is a convenient interface JsonSerializable which can be used to indicate that a PHP object can be serialized to JSON object. It has only one method which should be implemented by any class which implements this interface. The method is named jsonSerialize(). It's really easy to serialize an object to JSON object. Here is one example: <?php class ArrayValue implements JsonSerializable { public function __construct(array $array) { $this->array = $array; ...

   JSON,jsonSerialize,Inheritance,extends     2014-07-26 05:54:00

  Redis Cluster and Common Partition Techniques in Distributed Cache

In this post, I will discuss a few common partition techniques in distributed cache. Especially, I will elaborate on my understanding on the use of Redis Cluster. Please understand that at the time of writing, the latest version of Redis is 4.0.10. Many articles on the same topic have a different idea from this post. This is mainly because, those articles are probably outdated. In particular, they may refer to the Redis Cluster implementation in Redis 3. Redis Cluster has been improved...

   REDIS,DISTRIBUTED CACHE,CLOUD COMPUTING     2019-01-17 08:10:37

  Set file permission in Java

Prior to Java 6,  there is no good solution at the Java level to provide file permission management. You need to implement your own native methods or call the Runtime.exec() to invoke the system routine such as chmod in LInux. Since Java 6, Java introduces a set of methods which can be used to set the file permission at Java level. These methods include: File.setReadable(boolean); File.setWritable(boolean); FIle.setExecutable(boolean); File.setReadable(boolean, boolean); File.setWritable(bo...

   JAVA, FILE PERMISSION, POSIX,learnjava     2015-08-29 03:37:37

  Understanding database, instance and schema in Oracle database

Oracle database is the most popular database system among enterprises. To start working on Oracle database, some concepts must be understood first. They include database, instance, schema and user etc. And among these concepts, some have different meanings from those in other database systems such as MS SQL, MySQL, DB2. On the web, there are already some good posts which explain different concepts such as Ask Tom's database vs instances, Difference between database vs user vs schema. In this pos...

   DIFFERENCE,DATABASE,ORACLE DATABASE,INSTANCE,SCHEMA,USER     2016-12-14 23:30:56

  Some tips for writing proper emails

Email is now becoming one necessity of working. We may receive hundreds of emails everyday, they may from our colleagues, friends or clients. We need to exchange ideas, arrange meetings , asking for help etc though email in our work. A proper email can help us achieve what we want to achieve. Here we share some tips for writing a proper email.At the beginning of an email : Thank the reader is a good way to start the email, thank the reader may make the reader feel happy, especially when you ask ...

   EMAIL,TIP,FORMAT,TEMPLATE     2012-07-02 12:26:32

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