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It is believed that many inexperienced people are at a loss about the application and introduction of linux fork () function. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

First, introduction to fork

A process, including code, data, and resources assigned to the process. The fork () function creates a process that is almost identical to the original process through a system call, that is, two processes can do exactly the same thing, but if the initial parameters or the variables passed in are different, the two processes can also do different things.

After a process calls the fork () function, the system first allocates resources to the new process, such as the space to store data and code. Then copy all the values of the original process to the new process, except for the few values that are different from those of the original process. It's the equivalent of cloning yourself.

Let's look at an example:

/ * * fork_test.c * version 1 * Created on: 2010-5-29 * Author: wangth * / # include # include int main () {pid_t fpid; / / fpid represents the value returned by the fork function int count=0; fpid=fork (); if (fpid < 0) printf ("error in fork!") Else if (fpid = = 0) {printf ("i am the child process, my process id is% dban", getpid ()); printf ("I am the father's son / n"); / / Chinese looks more straightforward to some people. Count++;} else {printf ("i am the parent process, my process id is% DSPO", getpid ()); printf ("I am the father of the child / n"); count++;} printf ("Statistical result:% dBO", count); return 0;}

The result of the operation is:

I am the child process, my process id is 5574

I'm my father's son.

The statistical results are: 1

I am the parent process, my process id is 5573

I'm the father.

The statistical results are: 1

Before the statement fpid=fork (), only one process is executing this code, but after this statement, two processes are executing, the two processes are almost identical, and the next statement to be executed is if (fpid

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