Thread: C Processing Issues (oh fork()!)

Originally Posted by CheckMyBrain

Code:

int main(void) 
{
	fork();
	launch(parent);
}

The problem is probably the call to fork() here. This will cause the entire tree to get created twice -- you should be seeing 16 lines of output. Get rid of that initial fork(), and add a wait( NULL ) after calling launch() in main()

Whoa! What's this:

Code:

int main(void) 
{
	fork();
	launch(parent);
}

You will get two sets...I don't think the code you posted will even come remotely close to producing "8 processes. 3 of the processes are supposed to have 2 children each", since this very strongly implies that 5 processes should have no children.

But you seem to be creating 2 children, one with 2 children and a bunch of grandchildren and the other with just one grandchild:

Code:

parent -> child2 -> child4 -> child7 
                                         -> child8
                          -> child5
               child3 -> child6

Ok, so it worked once last night. I ran it again....it flubbed up.

Code:

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>

void launch( void (*func)() );
void parent();
void child2();
void child3();
void child4();
void child5();
void child6();
void child7();
void child8();
pid_t pid;

int main(void) 
{
	launch(parent);
	wait(NULL);
}

void launch( void (*func)() )
{
	if( fork() == 0 )
    {
        printf("My PID is %d, my parent is %d\n ", getpid(), getppid());
		func();
		exit( 0 );
    }
}

void parent()
{
	launch( child2 );
    launch( child3 );
	wait(NULL);
	wait(NULL);
}

void child2()
{
	launch( child4 );
    launch( child5 );
	wait(NULL);
	wait(NULL);
}

void child3()
{
	launch( child6 );
	wait(NULL);
}

void child4()
{
	launch( child7 );
    launch( child8 );
	wait(NULL);
	wait(NULL);
}

void child5()
{
}

void child6()
{
}

void child7()
{
}

void child8()
{
}

I was trying to clean it up/add comments, but it just spit out so much crap when I tried it! Then I reverted to the original, compiled it and still got like 20 lines then the end-of-line output.

Edit: Works in Putty. Not in WinSCP's terminal.

Originally Posted by CheckMyBrain

Edit: Works in Putty. Not in WinSCP's terminal.

That's good. You need to add <stdlib.h> for exit() -- it works anyway, since exit() is fine with a "default" int prototype -- but to be proper.

Anyway, I get:

[root~/C] ./a.out
My PID is 24288, my parent is 24287
My PID is 24289, my parent is 24288
My PID is 24290, my parent is 24289
My PID is 24291, my parent is 24290
My PID is 24292, my parent is 24290
My PID is 24293, my parent is 24289
My PID is 24294, my parent is 24288
My PID is 24295, my parent is 24294

Working by remote must be a pain. You should make some room on your HD and install some linux dude.