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Full Discussion: One parent, multiple children pipe with fork()
Top Forums UNIX for Beginners Questions & Answers One parent, multiple children pipe with fork() Post 303017920 by Corona688 on Thursday 24th of May 2018 03:25:36 PM
Old 05-24-2018
In short, how fork() really works:

Code:
pid_t pid=fork();

if(pid < 0)
{
    perror("couldn't fork");
    exit(1);
}

if(pid == 0) {
        // Child code
        do_stuff();
        exit(0);
}

// Parent code

 

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LEARN ABOUT SUNOS

setpgid

setpgid(2)							   System Calls 							setpgid(2)

NAME

       setpgid - set process group ID

SYNOPSIS

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

       int setpgid(pid_t pid, pid_t pgid);

DESCRIPTION

       The setpgid() function sets the process group ID of the process with ID pid to pgid.

       If pgid is equal to pid, the process becomes a process group leader. See intro(2) for more information on session leaders and process group
       leaders.

       If pgid is not equal to pid, the process becomes a member of an existing process group.

       If pid is equal to 0, the process ID of the calling process is used. If pgid is equal to 0, the process specified by pid becomes a  process
       group leader.

RETURN VALUES

       Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

       The setpgid() function will fail if:

       EACCES	       The  pid  argument  matches the process ID of a child process of the calling process and the child process has successfully
		       executed  one of the exec family of functions (see exec(2)).

       EINVAL	       The pgid argument is less than (pid_t) 0 or greater than or equal to PID_MAX, or the calling process has a controlling ter-
		       minal that does not support job control.

       EPERM	       The process indicated by the pid argument is a session leader.

       EPERM	       The  pid argument matches the process ID of a child process of the calling process and the child process is not in the same
		       session as the calling process.

       EPERM	       The pgid argument does not match the process ID of the process indicated by the pid argument, and there is no process  with
		       a process group ID that matches pgid in the same session as the calling process.

       ESRCH	       The pid argument does not match the process ID of the calling process or of a child process of the calling process.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       intro(2), exec(2), exit(2), fork(2), getpid(2), getsid(2), attributes(5), standards(5)

SunOS 5.10							    28 Dec 1996 							setpgid(2)
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