Once a new process is forked unless and untill parent / child synchronization is implemented in the code, there is no way to determine with the logic of code which would run first.
In the code that is being discussed, there is no such parent / child synchronization mechanism hence it is purely the discretion of the kernel to decide which one to run first ( had vfork been used, child is guaranteed to run first), though in most of the cases child runs first before the parent is executed.
Moreover the child and parent are using the common file pointer and before the parent could read the contents of the file child reads and moves the file pointer to read EOF. Thats why there is no file content being displayed on behalf of the parent process.
That could be checked as follows in a simple way,
In the parent modify the parent fscanf - code to print the return value, in most of the cases it would return -1 indicating before parent could start child had completed the processing and hence a '-1' being returned to that.
To specifically make a parent to read and child to wait before it could start, here is a weak way of doing it
in child code
(or)
have the file being read as a real huge file, then by default time slicing chances are there that parent gets a chance to read from the file before it encounters EOF
(Hope so, the sample file you had used is relatively small)
Hi guys,
I have the following code:
int main(int argc, char *argv)
{
int pid1,pid2,i=0;
pid1=fork();
i+=2;
if(!pid1) i++;
if(i%3) pid2=fork();
if (pid2==0)
{
printf("sea \n ");
i-=1;
}
if(i>=2)... (4 Replies)
Good evening everyone. I have my finals and I'm facing a problem:
I have a for cycle that is supposed to fork 2 children but somehow it forks only the first one.
What am I doing wrong ?
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>... (1 Reply)
Hello everyone, this is my first post.
I have a task to use a fork to create multiple processes and then use execlp to run another program to add 2 numbers.
The problem I am having is we are supposed to use the exit() call in the execlp to return the small integer. This is a bad way to... (3 Replies)
Hi, can someone please help me with creating mutltiple fork.. I was expecting something like this:
I am a child: 1 PID: 1215
I am a child: 2 PID: 1216
I am a child: 3 PID: 1217
I am a child: 4 PID: 1218
I am a child: 5 PID: 1219
I am a child: 6 PID: 1215
I am a child: 7 PID: 1216
I am a... (4 Replies)
i am a beginner of C, and i tired to fork multiple child and all of them belongs to same parents and each of child responsible for printing individual data.
but i don't have any idea how to do......
Can any body help? thanks a lot really. (7 Replies)
Hi All,
In my program i am handling SIGHUP signal. In the handler i fork and then exec on child process same binary file which is running. Parent process will die after 10 mins.
Now my child process which was exec with same binary file is not receiving SIGHUP signal. Below is the progran code:... (6 Replies)
I have this little program ...
int main(void){
printf("Before");
fork();
printf("After");
}
output is this.....
BeforeAfterBeforeAfter
Shouldnt it be.....BeforeAfterAfter
After parent is forked child receives the copy of program and continues from next statement... (3 Replies)
Hi,
I was honing my linux programming skill when this nuisance started bugging me. I wanted to create an empty file creator program. While creating a large file it must print # for progress bar. But the output shows it happening reverse way. ie. first it copies file and shows the progress... (7 Replies)
Hi,
I have developed a datastage job...which has many process running in parallel..but because of Fork Error my job is not working:(
Can any body help me out to solve this Fork error problem.:rolleyes:
My Os is SUNOS.
IS there any setting in Unix through admin where in if i set some paramter... (8 Replies)
Hi,
Consider the following piece of code:
int main(void) {
int i;
pid_t pidp;
for (i=0;i<4;i++) {
switch (pidp=fork()) {
case -1:
fprintf(stdout, "Error during fork.\n");
exit (1);
case 0:
fprintf(stdout, "From child: I am... (4 Replies)