Linux进程通信例子
Linux进程通信例子1.共享内存
使用:mmap
/*-------------map_normalfile1.c-----------*/
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
typedef struct{
char name;
intage;
}people;
main(int argc, char** argv) // map a normal file as shared mem:
{
int fd,i;
people *p_map;
char temp;
fd=open(argv,O_CREAT|O_RDWR|O_TRUNC,00777);
lseek(fd,sizeof(people)*5-1,SEEK_SET);
write(fd,"",1);
p_map = (people*) mmap( NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,
MAP_SHARED,fd,0 );
close( fd );
temp = 'a';
for(i=0; i<10; i++)
{
temp += 1;
memcpy( ( *(p_map+i) ).name, &temp,2 );
( *(p_map+i) ).age = 20+i;
}
printf(" initialize over \n ")；
sleep(10);
munmap( p_map, sizeof(people)*10 );
printf( "umap ok \n" );
}
/*-------------map_normalfile2.c-----------*/
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
typedef struct
{
char name;
intage;
}people;
void main(int argc, char** argv)// map a normal file as shared mem:
{
int fd,i;
people *p_map;
fd=open( argv,O_CREAT|O_RDWR,00777 );
p_map = (people*)mmap(NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,
MAP_SHARED,fd,0);
for(i = 0;i<10;i++)
{
printf( "name: %s age %d;\n",(*(p_map+i)).name, (*(p_map+i)).age );
}
munmap( p_map,sizeof(people)*10 );
}
3.管道
mkfifo
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
int main(int argc,char *argv[])
{
int fd;
char buf = "hello world!!!/n";
if((mkfifo("my_fifo", O_CREAT|O_RDWR|0666)) < 0)
{
perror("mkfifo");
exit(1);
}
if((fd = open("my_fifo" , O_WRONLY)) < 0)
{
perror("open");
exit(1);
}
if((write(fd,buf,strlen(buf)-1)) < 0)
{
perror("write");
exit(1);
}
return 0;
}
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
int main(int argc,char *argv[])
{
int fd;
char buf = "";
if((fd = open("my_fifo" , O_RDONLY)) < 0)
{
perror("open");
exit(1);
}
if((read(fd,buf,20)) < 0)
{
perror("read");
exit(1);
}
printf("%s" , buf);
return 0;
}
Makefile
overpass:main.o
g++ -g -ooverpass main.o -L. -lhiredis -lpthread -lcurl -lrt -lcrypto -lidn -lssl
main.o:main.cpp
g++ -g -c main.cpp -o main.o
clean:
rm -f *.o overpass
4.信号量
#include <stdio.h>
#include <linux/sem.h>
#define MAXNUMS 15
int get_sem_val(int sid,int semnum)//取得当前信号量
{
return(semctl(sid,semnum,GETVAL,0));
}
int main(void)
{
int sem_id;
int pid;
int rc;
struct sembuf sem_op;//信号集结构
union semun sem_val;//信号量数值
//建立信号量集，其中只有一个信号量
sem_id=semget(IPC_PRIVATE,1,IPC_CREAT|0600);//IPC_PRIVATE私有，只有本用户使用，如果为正整数，则为公共的；1为信号集的数量；
if (sem_id==-1){
printf("create sem error!\n");
exit(1);
}
printf("create %d sem success!\n",sem_id);
//信号量初始化
sem_val.val=1;
rc=semctl(sem_id,0,SETVAL,sem_val);//设置信号量,0为第一个信号量，1为第二个信号量,...以此类推；SETVAL表示设置
if (rc==-1){
printf("initlize sem error!\n");
exit(1);
}
//创建进程
pid=fork();
if (pid==-1){
printf("fork error!\n");
exit(1);
}
else if(pid==0){//一个子进程，消费者
for (int i=0;i<MAXNUMS;i++){
sem_op.sem_num=0;
sem_op.sem_op=-1;
sem_op.sem_flg=0;
semop(sem_id,&sem_op,1);//操作信号量，每次-1
printf("%d 消费者: %d\n",i,get_sem_val(sem_id,0));
}
}
else{//父进程，生产者
for (int i=0;i<MAXNUMS;i++){
sem_op.sem_num=0;
sem_op.sem_op=1;
sem_op.sem_flg=0;
semop(sem_id,&sem_op,1);//操作信号量，每次+1
printf("%d 生产者: %d\n",i,get_sem_val(sem_id,0));
}
}
exit(0);
}
Makefile
overpass:main.o
g++ -g -ooverpass main.o -L. -lhiredis -lpthread -lcurl -lrt -lcrypto -lidn -lssl
main.o:main.cpp
g++ -g -c main.cpp -o main.o
clean:
rm -f *.o overpass
一般是用管道即可
更多参考:http://www.cnblogs.com/linshui91/archive/2010/09/29/1838770.html
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