02-02-2011
Quote:
Originally Posted by
TWhitt24
I understand that. My question is how do I get the parent to fork and not the child.
Don't call fork() in the child if you don't want the child to fork. Your process gets told whether it's in the child by the return value of fork(), and can use that to decide whether to fork or not via if-statements like above. If you don't know how to use an if statement, refer to the above example, or post your own code so I can modify it with the appropriate logic.
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LEARN ABOUT ULTRIX
pthread_atfork
PTHREAD_ATFORK(3) Library Functions Manual PTHREAD_ATFORK(3)
NAME
pthread_atfork - register handlers to be called at fork(2) time
SYNOPSIS
#include <pthread.h>
int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));
DESCRIPTION
pthread_atfork registers handler functions to be called just before and just after a new process is created with fork(2). The prepare han-
dler will be called from the parent process, just before the new process is created. The parent handler will be called from the parent
process, just before fork(2) returns. The child handler will be called from the child process, just before fork(2) returns.
One or several of the three handlers prepare, parent and child can be given as NULL, meaning that no handler needs to be called at the cor-
responding point.
pthread_atfork can be called several times to install several sets of handlers. At fork(2) time, the prepare handlers are called in LIFO
order (last added with pthread_atfork, first called before fork), while the parent and child handlers are called in FIFO order (first
added, first called).
To understand the purpose of pthread_atfork, recall that fork(2) duplicates the whole memory space, including mutexes in their current
locking state, but only the calling thread: other threads are not running in the child process. The mutexes are not usable after the fork
and must be initialized with pthread_mutex_init in the child process. This is a limitation of the current implementation and might or
might not be present in future versions.
RETURN VALUE
pthread_atfork returns 0 on success and a non-zero error code on error.
ERRORS
ENOMEM insufficient memory available to register the handlers.
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
SEE ALSO
fork(2), pthread_mutex_lock(3), pthread_mutex_unlock(3).
LinuxThreads PTHREAD_ATFORK(3)