shmread.c

让你了解Unix进程间的通信是如何实现的

#include	"unpipc.h"

int
main(int argc, char **argv)
{
	int		i, id;
	struct shmid_ds	buff;
	unsigned char	c, *ptr;

	if (argc != 2)
		err_quit("usage: shmread <pathname>");

	id = Shmget(Ftok(argv[1], 0), 0, SVSHM_MODE);
	ptr = Shmat(id, NULL, 0);
	Shmctl(id, IPC_STAT, &buff);

		/* 4check that ptr[0] = 0, ptr[1] = 1, etc. */
	for (i = 0; i < buff.shm_segsz; i++)
		if ( (c = *ptr++) != (i % 256))
			err_ret("ptr[%d] = %d", i, c);

	exit(0);
}