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  What are some lesser known but useful Unix commands?

A few that come to mind, some less known, some more: xargs or parallel: run things in parallel, with lots of options sed and awk: more well-known but still super useful for processing text files, and faster than Python or Ruby m4: simple macro processor screen: powerful terminal multiplexing and session persistence yes: print a string a lot cal: nice calendar env: run a command (useful in scripts) look: find English words (or lines in a file) beginning with a string cut and paste and join: data...

   Linux,Unix,Command,Less used     2011-12-27 09:27:49

  Consistency between Redis Cache and SQL Database

Nowadays, Redis has become one of the most popular cache solution in the Internet industry. Although relational database systems (SQL) bring many awesome properties such as ACID, the performance of the database would degrade under high load in order to maintain these properties. In order to fix this problem, many companies & websites have decided to add a cache layer between the application layer (i.e., the backend code which handles the business logic) and the storage layer (i.e., the SQL d...

   REDIS,CACHE,DATABASE     2019-07-07 08:14:16

  Using MemoryMappedBuffer to handle large file in Java

When handling large files, it will largely affect the process speed while using traditional FileInputStream, FileOutputStream or RandomAccessFile since they trigger lots of read and write operations. In Java NIO, a new way of handling large file is introduced which is to use MmeoryMappedBuffer to create memory mapped file. Memory-mapped I/O uses the filesystem to establish a virtual memory mapping from user space directly to the applicable filesystem pages. With a memory-mapped file, you can pre...

   JAVA,IO,NIO     2015-11-13 01:58:08

  How to undo git changes?

When using git for version control, there is frequent need on undoing commits due to some unexpected changes. This post will introduce how to undo changes with git command in different cases. Undo commit A common undo case is that some commit needs to be reverted as the commit contains error. In this case, the code is already committed. The command to revert the commit is git revert HEAD This command will add new a commit to the existing head to undo the previous commit. It will not change the p...

   GIT,GIT RESET,GIT REVERT,GIT CHECKOUT     2019-12-28 02:21:47

  How to reset root password in MySQL 8

The user password in MySQL is stored in the user table, the password reset is actually to change the value of record in this table. To change the password in case the password is forgotten, the idea is to bypass the authentication of MySQL and get into the system and update the record password value with SQL command. In MySQL 5, one can start MySQL service with --skip-grant-tables option, this option will tell the service to skip loading the grant tables when starting, hence the root user can lo...

   MYSQL,PASSWORD,MYSQL 8     2018-12-24 21:27:13

  The Death of File Sharing

Last week’s violent government attack on the hugely popular site Megaupload — the U.S. government arresting Belgian citizens in New Zealand, of all places, and stealing at gunpoint servers bank accounts and property — has sent shock waves through the entire digital world. The first shock was the realization that the gigantic protest against legislative moves (SOPA and PIPA) that would smash the Internet turned out to be superfluous. The thing everyone wanted to prevent is al...

   File sharing,Death,Trend,Cloud     2012-02-01 04:44:06

  Add compiler argument to build Maven project

Maven is a software project to manage a project's build, reporting and documentation from a central piece of information. It's now widely used t build and deploy projects. It can help automatically maintain the dependencies of projects. There is a central project configuration file named pom.xml. Here you can configure the project you want to build.  In this post, we will show you how to add compiler argument when using javac to compile Java source code. Sometimes we need to pass compi...

   Maven,compiler argument, compiler option, Java 8     2015-04-10 21:59:00

  How to password protect a Winzip file

Winzip files are great ways of sharing documents and images of large sizes over the web or through email, since their reduced size makes it possible for them to be sent and received. Also, it is easier to manage one attachment than multiple. But what if the file contains sensitive information you don’t want snoopers to see? Simply add a password protection in Winzip. Adding a password will ensure more security and reliability of the transported files. How to add a Password to your Zip Fil...

   DATA SECURITY,WINZIP     2019-08-29 11:42:41

  Get the 48×48 or 256×256 icon of a file on Windows

Getting the 16×16 and 32×32 icons on Windows is relatively easy and is often as simple as one call to ExtractIconEx. However, getting the extra large (48×48) and jumbo (256×256) icons introduced respectively by XP and Vista is slighly more complex. This is normally done by: Getting the file information, in particular the icon index, for the given file using SHGetFileInfoRetrieving the system image list where all the icons are storedCasting the image list to an IImageList interf...

   File icon,File extension,Association,Large icon,Windows     2012-03-23 09:35:17

  Understand diff in Unix

diff is an important tool program in Unix. It is used to compare differences of two files, it is the foundation for code version control. If you type : $ diff <file_before_change> <file_after_change> diff will tell you what's the difference between these two files. The result may not be so easy to understand, so now I will show you how to understand diff. 1. 3 formats of diff diff has 3 formats due to historic reasons. normal diff context diff unified diff 2. Demo files For easy d...

   diff,Unix,version control,git     2012-09-03 10:49:36

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