fork and vfork

creatory

/*this .c file demonstrates how to use fork function to generate a new process*/
/*filename:fork.c
  time:08/06/2009
  author:creatory@mail.com
  when fork success,the process scheduled sequence is unsure.
  Every one can be scheduled by the scheduled process firstly.
  So the result is not sure.
*/
#include
#include   //fork
#include  //exit
int main(void){
    pid_t pid;
    if((pid=fork())==-1){
        printf("fork error.\n");
        exit(1);
    }else if(pid==0){
        //child
        printf("this is child process.\n");
        
    }else{
        //parent
        printf("this is parent process.\n");
    }
    return 0;
}
/* this file demonstrates how to use vfork function
filename:vfork.c
time:08/06/2009
author:creatory@mail.com
Note:
    Call vfork will hang up the parent process until the child process terminate or it call exec function.
So the result is always child process execute firstly,then parent process.It's sure.
*/
/*remain problem:why the end must be exit(0) not "return 0".
if "return 0" then generate "segmentation fault"
*/
#include  //exit
#include  //vfork
#include
#include  //printf
int main(void){
    pid_t pid;
    if((pid=vfork())<0){
        printf("vfork error!\n");
        exit(1);
    }
    else if(pid==0){
        //the child process
        printf("Child process is printing.\n");
        
    }else{
        //the parent process
        printf("the parent is printing.\n");
    }
//    return 0;
    exit(0);
}


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