2.无名管道

2.1.管道创建和关闭

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char **argv)
{
	static const char mesg[] = "Hello world!";	
	char buf[BUFSIZ];
	ssize_t rcount, wcount;
	int pipefd[2];
	size_t len;

    /*创建管道*/
	if (pipe(pipefd) < 0) {
		fprintf(stderr, "%s: pipe failed: %s\n", argv[0],
			strerror(errno));
		exit(1);
	}
	printf("PIPE: Read end = fd %d, write end = fd %d\n",
		pipefd[0], pipefd[1]);

    /*写管道*/
	len = strlen(mesg);
	if ((wcount = write(pipefd[1], mesg, len)) != len) {
		fprintf(stderr, "%s: write failed: %s\n", argv[0],
			strerror(errno));
		exit(1);
	}
	printf("Write <%s> via pipe\n", mesg);

    /*读管道*/
	if ((rcount = read(pipefd[0], buf, BUFSIZ)) != wcount) {
		fprintf(stderr, "%s: read failed: %s\n", argv[0],
			strerror(errno));
		exit(1);
	}

	buf[rcount] = '\0';
    /*添加字符串终止字符*/
	printf("Read <%s> from pipe\n", buf);

    /*关闭管道*/
	close(pipefd[0]);
	close(pipefd[1]);
	return 0;
}