Lots of people would think what the address 127.0.0.1 is when first seeing this address. In fact, 127.0.0.1 is a loopback address which refers to the local machine. It is generally used for local testing. When typing ping 127.0.0.1 on local command console, it will send network packets to local IP/TCP layer to test whether IP/TCP works properly or not. To those who are used to use localhost, it is actually mapped to 127.0.0.1 by default. There are hosts files in the system which store this mapping. Hence normally these two can be interchanged.# localhost name resolution is handled within ...

JSON now becomes a very popular data format because of its simplicity and light-weight. Nowadays many RESTful APIs will offer a choice of exchanging JSON data between the server and client. Sometimes the data may not be formatted and it cannot be easily read by human beings. It's frequently desired that the unformatted JSON data should be formatted before read.Today we will show a few ways to format JSON data on Ubuntu. Assume we have a json file test.json with below content.{ "title": "Test", "description": "Sample description" }The normal cat command will output below content.postman@postman...

1. There is an option when you set up clock on installing Linux: system clock users UTC, so what does UTC mean?It's Universal Time Coordinated(UTC), there are two different times in GPS system: one is UTC , the other one is LT(Local Time). The difference between these two is just the timezone difference, UTC is the time in timezone 0. If the local time in Beijing is 8 o'clock in the morning, then UTC time is 0 o'clock, which is a 8 hour difference.2. In Linux, when we use date to check the time, we may get 17 December,2008 Wednesday 09:04:14 CST. What does CST ,mean here?CST is China Standard ...

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 default one on most Linux distributions.There are two very important configuration files for bash : bas...

I don't think using Emacs can improve one's programming skills, I don't think some famous people used Emacs before can provide something, either. But these famous people encouraged me to learn Emacs when I wanted to give it up. Here I created a list of famous Emacs users.Most of people in this list are not famous because they developed or used Emacs, but they are famous and also use Emacs.Joe Armstrong -- Erlang's authorIn The Setup, Joe mentioned that "I write books using XML markup in emacs (nxml mode)" and "I write code in Emacs".Amelia Andersdotter -- PoliticianIn an interview, Amelia ment...

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 space with 0 gravity, astronauts cannot use pen to write. So they spend much money on developing a pen...

1. slYou will see a train moving from the right to left on the screen.Install : $ sudo apt-get install slRun : $ slIt has options like -aiFe:-a An accident seems to happen. You'll feel pity for people who cry for help.-l shows little one.-F It flies.-e Allow interrupt by Ctrl+C.We can also make fun of other people by setting an alias like below:$alias ls=slWhen the user types ls, he will see the train instead of the file list.2. fortuneOutput one statement, it can be a joke, or famous saying. Or if you install the Chinese version, you will get Tang poem as well.Install : $sudo apt-get install ...

As a programmer or system administrator, we have more chances of working on *nix platforms. It's tough experience when first start use *nix as we need to face a black screen without knowing what's behind it. Now, if we can have some resources to rely on, then we will find the beautify of *nix. They are fast, efficient and most importantly sexy. Below are some great tips for helping Linux users get used to Linux.This list is a bit long. So be patient. To get more information on a command mentioned, first try "man ". The best way to learn something is to read the specification first then practic...