Fork creates a new process. The newly created process is a child process. It is a copy of the subsequent code of the parent process. It is usually used as a multi-process server. It can also run independent code in the child process.
Use getpid to determine whether the current process is a child process or a parent process.
Consider the following example:
The following is the quoted content:
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
int main()
{
pid_t pid;
static int n = 0;
printf("fork!n");
switch (pid = fork())
{
case-1:
{
/* ..pid.-1.fork.... */
/* ....... */
/*..........*/
perror("The fork failed!");
break;
}
case 0:
{
/* pid.0.... */
printf("[child]i am child!n");
printf("[child]getpid=[%d]n", getpid() );
printf("[child]pid=[%d]n", pid );
break;
}
default:
{
/* pid..0.... */
printf("[parent]i am parent!n" );
printf("[parent]getpid=[%d]n",getpid() );
printf("[parent]pid=[%d]n",pid );
break;
}
}
printf("n=[%d]n", n++); return 0;
} |
This example is compiled with gcc under Linux, and the running results are as follows:
The following is the quoted content:
fork!
[child]i am child!
[child]getpid=[7422]
[child]pid=[0]
n=[0]
[parent]i am parent!
[parent]getpid=[7421]
[parent]pid=[7422]
n=[0] |
