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Python Subprocess Module

Subprocess A running program is called a  process . Each process has its own system state, which includes memory, lists of open files, a program counter that keeps track of the instruction being executed, and a call stack used to hold the local variables of functions. Normally, a process executes statements one after the other in a single sequence of control flow, which is sometimes called the main thread of the process. At any given time, the program is only doing one thing. A program can create new processes using library functions such as those found in the os or subprocess modules such as  os.fork() ,  subprocess.Popen() , etc. However, these processes, known as  subprocesses , run as completely independent entities-each with their own private system state and main thread of execution. Because a subprocess is independent, it executes concurrently with the original process. That is, the process that created the subprocess can go on to work on other thing...

How communication happens across ..? (Explained from the scratch)

okay.. in this article I am going to explain how communication happens between the systems from the scratch. For this, first we need to understand the basic of network hardware in the computer system. Network hardware is the main crucial thing that makes a computer system to communicate with the other computers. The hardware that I was talking about is nothing but an NETWORK ADAPTER. Network adapter is also called network card or  network interface card (NIC). Network adapter is fixed to the hardware of the computer which consists of ports that makes the computer to connect to the network. The ports in network adapter are RJ-45 ports. RJ means Registered Jack. RJ is standardized physical network interface. The standard designs are RJ-11,RJ-45..etc. RJ-45  just looks like a port that is used by the landline telephone port. But, that is different from RJ-45 port. The port used by the telephone is RJ-11, RJ-11 is smaller than RJ-45. The cable used to connect the port is twi...

How To Configure a Linux Service to Start Automatically After a Crash or Reboot

Part 1: Practical Examples Tutorial Series Introduction This tutorial shows you how to configure system services to automatically restart after a crash or a server reboot. The example uses MySQL, but you can apply these principles to other services running on your server, like Nginx, Apache, or your own application. We cover the three most common init systems in this tutorial, so be sure to follow the one for your distribution. (Many distributions offer multiple options, or allow an alternate init system to be installed.) System V  is the older init system: Debian 6 and earlier Ubuntu 9.04 and earlier CentOS 5 and earlier Upstart : Ubuntu 9.10 to Ubuntu 14.10, including Ubuntu 14.04 CentOS 6 systemd  is the init system for the most recent distributions featured here: Debian 7 and Debian 8 Ubuntu 15.04 and newer CentOS 7 Background Your running Linux or Unix system will have a number of background processes executing at any time. These proc...