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help in C of fork() problem

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Top Forums Programming help in C of fork() problem
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Old 02-26-2011
Quote:
Originally Posted by wendy1089
how can i pass the argv value from parent to children
They already have it. They get a copy of it just like they get a copy of everything else.

Quote:
i want first child to read argv first number and second child read second,etc. how can i do that?
Like I've been saying all along, use the value of i in the child. It gets a copy from the instant the parent called fork(), so child 0 gets 0, child 1 gets 1, child 2 gets 2, child 3 gets 3, child 4 gets for, and so forth.

You may be overthinking this. All your question amounts to is "how do I use an array" and the answer is array[index]. for most purposes argv starts at 1, not 0, so argv[i+1]. Be careful not to exceed the value of argc or you will crash!
Quote:
also how to save pid into array? i tried to use int for it data type, but it seems not successful.
pid_t should work, but int should also work, so I suspect your program failed for other reasons. Not having psychic powers, I can't see from here why it's not working. Post your code!
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LEARN ABOUT MOJAVE

pthread_atfork

PTHREAD_ATFORK(3)					   BSD Library Functions Manual 					 PTHREAD_ATFORK(3)

NAME

     pthread_atfork -- register handlers to be called before and after fork()

SYNOPSIS

     #include <pthread.h>

     int
     pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));

DESCRIPTION

     The pthread_atfork() function declares fork handlers to be called before and after fork(2), in the context of the thread that called fork(2).

     The handlers registered with pthread_atfork() are called at the moments in time described below:

     prepare  Before fork(2) processing commences in the parent process.  If more than one prepare handler is registered they will be called in
	      the opposite order they were registered.

     parent   After fork(2) completes in the parent process.  If more than one parent handler is registered they will be called in the same order
	      they were registered.

     child    After fork(2) processing completes in the child process.	If more than one child handler is registered they will be called in the
	      same order they were registered.

     If no handling is desired at one or more of these three points, a null pointer may be passed as the corresponding fork handler.

     Important: only async-signal-safe functions are allowed on the child side of fork().  See sigaction(2) for details.

RETURN VALUES

     If successful, the pthread_atfork() function will return zero.  Otherwise an error number will be returned to indicate the error.

ERRORS

     The pthread_atfork() function will fail if:

     [ENOMEM]		The system lacked the necessary resources to add another handler to the list.

SEE ALSO

     fork(2), pthread(3)

STANDARDS

     The pthread_atfork() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').

BSD
								   June 21, 2004							       BSD