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SEARCH KEYWORD -- File system structure

  Understanding How is Data Stored in RDBMS

We all know that DBMS (database management system) is used to store (a massive amount of) data. However, have you ever wondered how is data stored in DBMS? In this post, we will focus on data storage in RDBMS, the most traditional relational database systems. Physical Storage Data can be stored in many different kinds of medium or devices, from the fastest but costy registers to the slow but cheap hard drives, or even magnetic tapes. Nowadays, IaaS providers such as AWS...

   RDBMS,DATABASE     2019-02-04 09:25:36

  My frequently used Linux commands

In our day to day work. We may have many chances working on Linux/Unix systems. There are many things we may need to do, checking logs, navigating in directories, creating file or installing software. We may use many commands to complete the work, such as ls, mkdir, cd etc. Below are my frequently used Linux commands or programs recently: pwd : print working directory, sometimes I need to check which working directory I am in in order to know where to go next. ls : List current directory files,...

   Linux,Command,Program     2012-08-16 15:09:42

  Add Sublime Text to your context menu on right click

When opening a text file, you may be used to right click on the file to be opened and then choose the application which can open the file from the context menu. On the context menu, you may see a menu item like "Edit with Notepad++". Nowadays many people especially programmers like to use Sublime Text, but by default this application will not show on the context menu when you right click on a file. There is now frequent request to add this application to the context menu. Here we show a simple b...

   SUBLIME TEXT,CONTEXT MENU,WINDOWS     2015-10-19 08:51:25

  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

  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

  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

  Fix issue docker-credential-desktop not installed or not available in PATH on Mac

Sometimes you may encounter below issue while running docker-compose on MacOS. Traceback (most recent call last): File "docker-compose", line 6, in <module> File "compose/cli/main.py", line 71, in main File "compose/cli/main.py", line 127, in perform_command File "compose/cli/main.py", line 1085, in up File "compose/cli/main.py", line 1081, in up File "compose/project.py", line 527, in up File "compose/service.py", line 354, in ensure_image_exists File "compose/service.py",...

   MACOS,DOCKER,DOCKER-COMPOSE     2020-06-23 03:25:16

  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

  Common usage of ls command in Linux

In Linux, ls might be one of the most frequently used commands. It is used to list files in a specific directory. In most cases, we may just use ls -l to list the files under a directory. But have you explored other usages of this command. In this post, we will summarise some other common usages of ls command Assuming we have below directory structure in our system, let's see them using tree command. List details of the files If we want to list the details of the files in /home/alvin/test_...

   LINUX,SHELL,LS     2018-12-16 03:00:42

  GoLang to build smaller executable file

Normally the executable file built with go is a bit large, it is always desired that a smaller executable file should be generated though. In this post, a couple of ways to reduce the size of the executable will be introduced. The end effect is that the executable file size would be much less than the normal generated one. The file which is built normally has below size. Mode LastWriteTime Length Name ---- ------------- ------ ---- -a---- 12/14...

   GOLANG,EXECUTABLE     2019-12-13 20:10:45

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