SEARCH KEYWORD -- unix


  Convert time to Unix time

Unix time is defined as the number of seconds that have elapsed since midnight Coordinated Universal Time (UTC), 1 January 1970,not counting leap seconds. It is used widely in Unix-like and many other operating systems and file formats. It is neither a linear representation of time nor a true representation of UTC. Unix time may be checked on some Unix systems by typing date +%s on the command line. Sometimes it's a bit difficult to compare times stored in different applications or systems with ...

   UNIX time, Oracle DATE, conversion, timestamp     2013-01-19 09:04:17

  Carriage return and line feed

In programming and document editing, we may frequently encounter carriage return and line feed, i.e the well known CRLF.  But do you know about the history and difference of carriage return and line feed? Before computer came out, there was a type of teleprinter called Teletype Model 33. It can print 10 characters each second. But there is one problem with this, after finishing printing each line, it will take 0.2 second to move to next line, which is time of printing 2 characters. If a new...

   CR,CARRIAGE RETURN,LINE FEED,LF,NEW LINE,CRLF     2017-02-19 08:29:23

  Unix Philosophy

First, let me tell two stories.The first one is one Japan soap factory had a problem that they sometimes shipped empty boxes to the customer without soap inside. So they spend much time and money to invent a X-ray machine to check whether the soap box is empty.The same thing happens in a small factory which doesn't have too much money. The solution of them to solve this problem is they use a desk fan to blow the empty boxes out of the belt and into a bin.The second story is NASA finds that in sp...

   Unix Philosophy,Simple,Rules     2012-05-06 06:49:26

  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

  What is good design?

Some quotes about good design from a Germany designer Dieter Rams in documentary "Objectified": Good design should be innovative Good design should make a product useful Good design is aesthetic design Good design will make a product understandable Good design is honest Good design is unobtrusive Good design is long-lived Good design is consistent in every detail Good design is environmentally friendly Good design is as little design as possible This brings up a question -- what...

   METRO,SIMPLICITY,GOOD DESIGN,PRINCIOPLE,UNIX PHILOSOPHY     2012-05-09 06:48:11

  Socket programming tips in Solaris

I sponsored a topic in stackoverflow.com, and hoped the programmers can share the socket programming tips in different UNIX flavors. But unfortunately, the responders are few. So I can only share my socket programming tips in Solaris at here (the Chinese version can be found there): 1. Use the following link options: "-lresolv -lnsl -lsocket";2. Solaris doesn't provide socket options: SO_SNDTIMEO and SO_RCVTIMEO(Why does Solaris OS define SO_SNDTIMEO and SO_RCVTIMEO socket options...

   C,Solaris,socket,     2014-05-09 23:01:03

  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

  Severe SSL 3.0 vulnerability to be released

According to The Register, another severe security vulnerability has been found in the widely used SSL v3 protocol. Until now, it's still in patch phase and the details of this vulnerability is expected to be released today. There are a few widely impacted security vulnerabilities revealed this year and they bring people's attention to the long existing security concerns. Previously, we have seen the HeartBleed issue and also the recently ShellShock issue. Both of them occur in popular libraries...

   SSL,Security vulnerability, The Register     2014-10-14 22:22:39

  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

  A trap about PHP random number

The method to get random number in PHP is very simple, we only need to use rand() function. int rand ( int $min , int $max ) One function call can return the random number in a specified range. But in fact, the random number in computer is actually pseudorandomness, generally to increase the randomness, we may set a random seed before calling rand(). void srand ([ int $seed ] ) According to other language features, we should pass a time value as a parameter to the srand() function, generally...

   PHP,rand,srand,mt_rand     2013-06-07 09:10:10

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