Linux管道的操作

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                           管道和进程的创建

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#include<stdlib.h>
 #include<sys/stat.h>
 #include<string.h>
 #include<errno.h>
 int main()(int argc,char **argv)
 if(argc<2)
 {
 	fprintf(stdout,"Usage:%s<filename>n",argv[0];
 	exit(1);
 	}
 	//int mkfifo(const char *path,mode_t mode);
 	if(mkfifo(argv[1],0644)<0）	
     {
 		fprintf(stderr,"mkfifo() failed:%sn"，strerror(errno));
 		exit(1);
 		}
 		return 0;
 		}

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这几行代码可以创建一个管道
**（2）写进程的创建**

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#include<stdio.h>
 	#include<stdlib.h>
 	#include<unistd.h>
 	#include<sys/stat.h>
 	#include<fcntl.h>
 	#include<string.h>
 	#include<errno.h>
 	int main(int argc,char *argv[])
 	{
 		int fd;
 		char str[1024];
 		ssize_t n;
 		if(argc<2){
 		printf("Please input 'fifo name' after %sn",argv[0];
 		exit(1);
 		}
 		mkfifo(argv[1],0644);
 		if((fd=open(argv[1],O_WRONLY))<0){
 		printf("Opening Write_fifo Failed.n");
 		exit(1);
 		}
 		printf("Write_fifo is ready.n");
 		printf("Waitting message....nn");
 		while(1){
 		printf("Please input:n");
 		fgets(str,sizeof(str),stdin);
 		write(fd,dtr,strlrn(str)+1);
 		if(!strcmp(str,":qn")){
 		printf("Write_fifo closed.n");
 		break;
 		}
 		}
 		close(fd);
 		return 0;
 		}

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	此为写进程的创建。

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
int search(char *str1, char *str2);
int count = 0;
int main(int argc, char *argv[])
{
	int fd1, fd2;
	char str1[1024], str2[1024];
	ssize_t n;
	if (argc < 2) {
		printf("Please input 'fifo name' after %sn", argv[0]);
		exit(1);
	}
	if ((fd1 = open(argv[1], O_RDONLY)) < 0) {
		printf("Opening Read_fifo failed.n");
		exit(1);
	}
	
	if ((fd2 = open("./target.txt", O_RDONLY)) < 0) {
		printf("Opening Search_file failed.n");
		exit(1);
	}
	lseek(fd2, 0, SEEK_SET);
	printf("Write_fifo is ready.n");
	printf("Waiting message......nn");
	while (read(fd1, str1, sizeof(str1)) > 0) {	
		if (!strcmp(str1, ":qn")) {
			printf("Read_fifo closed.n");
			break;
		}
		str1[strlen(str1) - 1] = '';
		printf("Your message is: %sn", str1);
		printf("Now searching '%s' in 'target.txt' ....n", str1);
		while(1) { 
			n = read(fd2, str2, sizeof(str2));
			if (n < 1024) {
				search(str2, str1);
				lseek(fd2, 0, SEEK_SET);
				break;
			}
			if (n == sizeof(str2))
				search(str2, str1);
		}
		printf("Appeared %d times!n", count);
		count = 0;
	}
	close(fd1);
	close(fd2);
	return 0;
}
int search(char *str1, char *str2) {
	char *temp;
	while (strlen(str1)) {
		temp = strstr(str1, str2);
		if (temp == NULL)
			break;
		count += 1;
		temp = &temp[strlen(str2)];
		str1 = temp;
	}
	return 0;
}