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  Differences between bashrc and profile in Linux

After login to a Linux system, the command console will show up with a prompt label such as # or ~, a shell command can be typed after this prompt and the system can execute the command thereafter. All these operations are handled by shell. Shell is a command language interpreter that executes commands read from the standard input device (keyboard) or from a file. There are different types of shells such as bash, ksh, csh etc. The most commonly used of them is bash and it's also the de...

   LINUX,PROFILE,BASH,BASHRC,.BASHRC,.PROFILE     2016-11-05 22:17:51

  Strict mode in JavaScript

1. Introduction In addition to normal mode, ECMAScript 5 includes the other mode : strict mode. It means it will make JavaScript codes execute in a more strict environment. The purposes to have strict mode are: Remove some unreasonable and parts of JavaScript syntax. Reduce some of the quirk behaviors. Remove some insecure parts of code execution. Make the execution environment more secure Improve interpret efficiency and increase the execution speed Build foundation for future JavaScript versi...

   JavaScript, Strict mode. Introduction     2013-01-17 05:00:26

  System programming is still there

System programming is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. But nowadays more...

   System programming     2014-02-27 05:46:48

  Your Code is My Hell

It occurred to me recently that my experience as a Rails developer may be somewhat unique.I often get brought in to help preexisting Ruby/Rails projects evolve and mature in a sustainable way. As a result, the vast majority of Ruby projects I’ve worked on have been well-established by the time I arrived. In fact, offhand I can only think of one commercial greenfield Ruby project I’ve participated in. All the rest have been “legacy” from my perspective, in the ...

   Code style,Clean code,Code paradigm     2011-09-15 08:39:16

  How many bytes a boolean value takes in Java?

Have you ever wondered how many bytes a boolean value takes in Java? One byte, this might be the answer comes out of your mind right away. But is it? Let's dig in more. Per Oracle documentation on boolean value definition, there is below statement: boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defin...

   JAVA,INTERVIEW,SIZE,BOOLEAN     2020-02-29 02:49:18

  Books for entry level C programmers

In computing, C is a general-purpose programming language initially developed by Dennis Ritchie between 1969 and 1973 at Bell Labs Its design provides constructs that map efficiently to typical machine instructions, and therefore it found lasting use in applications that had formerly been coded in assembly language, most notably system software like the Unix computer operating system.To learn C, we need to read many C books and have many practices. Here we summarize a list of C books which may h...

   C,Book,Beginning     2012-07-26 14:00:51

  /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

  Python internals: adding a new statement to Python

This article is an attempt to better understand how the front-end of Python works. Just reading documentation and source code may be a bit boring, so I’m taking a hands-on approach here: I’m going to add an until statement to Python. All the coding for this article was done against the cutting-edge Py3k branch in the Python Mercurial repository mirror. The until statement Some languages, like Ruby, have an until statement, which is the complement to while (until num == 0 is equi...

   Python,New statement,Research,Addition     2012-03-12 07:32:24

  Shortcut keys in Sublime Text 3(Animated demo)

Sublime Text 3 is a light weight code editor which supports lots of languages. It has lots of shortcuts and plugins easing work of programmers. In this post, we will introduce some shortcuts supported in Sublime Text 3 and show how powerful they are. 1. Select sibling matching(equal) word (Ctrl + D) Put the cursor on one word, press Ctrl + D to select the word, then press Ctrl and following by pressing D, it will select next matching word. The number of Ds pressed will mean number of matching wo...

   TIPS,SHORTCUT KEY,SUBLIME TEXT     2016-04-28 02:41:28

  Unix directory hierarchy history

As a beginner user of Unix or Linux, people would frequently get confused about the use of different directories of the system.  For example, there is a /bin directory under root(/), it is used to store binary files. However, there are /usr/bin and /usr/local/bin under /usr which are used for storing binary files as well. Some systems even have /opt/bin. What are the differences among them? Though there are articles explaining different directories in *nix such as Filesystem Hierarchy Stan...

   UNIX,LINUX,FILESSYTEM,DIRECTORY HIERARCHY,HISTORY     2016-10-21 23:47:17

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