Linux进程间通信类型含示例

1：Linux进程间通信类型

2:   管道（pipe）和有名管道（FIFO）。

3:  信号（signal)，见signal函数、sigaction函数及信号集操作函数和信号的发送和捕捉函数(alarm、kill、raise、pause、 sleep、abort)。

4:  共享内存，见共享内存函数（shmget、shmat、shmdt、shmctl）及其范例。

5:  消息队列，见消息队列函数(msgget、msgctl、msgsnd、msgrcv)及其范例。

6:  信号量，见信号量函数（semget、semop、semctl）及其范例。

7:  套接字（socket），入门见SOCKET网络编程 （通俗易懂入门篇）

                                     若想全面，可见TCP/IP模型，socket主要函数说明和socket地址说明及转换函数，

                                      及listen()函数中backlog参数分析，linux进程间通信--消息队列相关函数（ftok）详解。

附4：共享内存中程序如下：

//父子进程
#include
#include
#include
#include
#include
#include
#define SIZE 1024
int main()
{
int shmid ;
char *shmaddr ;
struct shmid_ds buf ;
int flag = 0 ;
int pid ;
shmid = shmget(IPC_PRIVATE, SIZE, IPC_CREAT|0600 ) ;
if ( shmid <0 ) {
perror("get shm ipc_id error") ;
return -1 ;
}
pid = fork() ;
if ( pid == 0 ) {
shmaddr = (char *)shmat( shmid, NULL, 0 ) ;
if ( (int)shmaddr == -1 ) {
perror("shmat addr error") ;
return -1 ;
}
strcpy( shmaddr, "Hi, I am child process!\n") ;
shmdt( shmaddr ) ;
return 0;
} else if ( pid > 0) {
sleep(3 ) ;
flag = shmctl( shmid, IPC_STAT, &buf) ;
if ( flag == -1 ) {
perror("shmctl shm error") ;
return -1 ;
}
printf("shm_segsz =%d bytes\n", buf.shm_segsz ) ;
printf("parent pid=%d, shm_cpid = %d \n", getpid(), buf.shm_cpid ) ;
printf("chlid pid=%d, shm_lpid = %d \n",pid , buf.shm_lpid ) ;
shmaddr = (char *) shmat(shmid, NULL, 0 ) ;
if ( (int)shmaddr == -1 ) {
perror("shmat addr error") ;
return -1 ;
}
printf("%s", shmaddr) ;
shmdt( shmaddr ) ;
shmctl(shmid, IPC_RMID, NULL) ;
} else {
perror("fork error") ;
shmctl(shmid, IPC_RMID, NULL) ;
}
return 0 ;
}
shm_segsz =1024 bytes
parent pid=12, shm_cpid = 12
chlid pid=13, shm_lpid = 13
Hi, I am child process!
//写端进程
#include
#include
#include
#include
#include
#include
typedef struct{
char name[8];
int age;
} people;
int main(int argc, char** argv)
{
int shm_id,i;
key_t key;
char temp[8];
people *p_map;
char pathname[30] ;
strcpy(pathname,"/tmp") ;
key = ftok(pathname,0x03);
if(key==-1)
{
perror("ftok error");
return -1;
}
printf("key=%d\n",key) ;
shm_id=shmget(key,4096,IPC_CREAT|IPC_EXCL|0600);
if(shm_id==-1)
{
perror("shmget error");
return -1;
}
printf("shm_id=%d\n", shm_id) ;
p_map=(people*)shmat(shm_id,NULL,0);
memset(temp, 0x00, sizeof(temp)) ;
strcpy(temp,"test") ;
temp[4]='0';
for(i = 0;i<3;i++)
{
temp[4]+=1;
strncpy((p_map+i)->name,temp,5);
(p_map+i)->age=0+i;
}
shmdt(p_map) ;
return 0 ;
}
key=52772138
shm_id=0
//读端进程
#include
#include
#include
#include
#include
#include
typedef struct{
char name[8];
int age;
} people;
int main(int argc, char** argv)
{
int shm_id,i;
key_t key;
people *p_map;
char pathname[30] ;
strcpy(pathname,"/tmp") ;
key = ftok(pathname,0x03);
if(key == -1)
{
perror("ftok error");
return -1;
}
printf("key=%d\n", key) ;
shm_id = shmget(key,0, 0);
if(shm_id == -1)
{
perror("shmget error");
return -1;
}
printf("shm_id=%d\n", shm_id) ;
p_map = (people*)shmat(shm_id,NULL,0);
for(i = 0;i<3;i++)
{
printf( "name:%s\n",(*(p_map+i)).name );
printf( "age %d\n",(*(p_map+i)).age );
}
if(shmdt(p_map) == -1)
{
perror("detach error");
return -1;
}
return 0 ;
}

附5：消息队列中程序如下：

#include
#include
#include
#include
#include
#include
#define TEXT_SIZE 512
struct msgbuf
{
long mtype ;
char mtext[TEXT_SIZE] ;
} ;
int main(int argc, char **argv)
{
int msqid ;
struct msqid_ds info ;
struct msgbuf buf ;
struct msgbuf buf1 ;
struct msgbuf buf2 ; //
int flag ;
int sendlength, recvlength ;
msqid = msgget( IPC_PRIVATE, 0666 ) ;
if ( msqid <0 )
{
perror("get ipc_id error") ;
return -1 ;
}
buf.mtype = 1 ;
strcpy(buf.mtext, "happy new year!") ;
sendlength = sizeof(struct msgbuf) - sizeof(long) ;
flag = msgsnd( msqid, &buf, sendlength , 0 ) ;
if ( flag <0 )
{
perror("send message error") ;
return -1 ;
}
buf.mtype = 3 ;
strcpy(buf.mtext, "good bye!") ;
sendlength = sizeof(struct msgbuf) - sizeof(long) ;
flag = msgsnd( msqid, &buf, sendlength , 0 ) ;
if ( flag <0 )
{
perror("send message error") ;
return -1 ;
}
flag = msgctl( msqid, IPC_STAT, &info ) ;
if ( flag <0 )
{
perror("get message status error") ;
return -1 ;
}
printf("uid:%d, gid = %d, cuid = %d, cgid= %d\n" ,
info.msg_perm.uid, info.msg_perm.gid, info.msg_perm.cuid, info.msg_perm.cgid ) ;
printf("read-write:%03o, cbytes = %lu, qnum = %lu, qbytes= %lu\n" ,
info.msg_perm.mode&0777, info.msg_cbytes, info.msg_qnum, info.msg_qbytes ) ;
system("ipcs -q") ;
recvlength = sizeof(struct msgbuf) - sizeof(long) ;
memset(&buf1, 0x00, sizeof(struct msgbuf)) ;
flag = msgrcv( msqid, &buf1, recvlength ,3,0 ) ;
if ( flag <0 )
{
perror("recv message error") ;
return -1 ;
}
printf("type=%d, message=%s\n", buf1.mtype, buf1.mtext) ;
memset(&buf2, 0x00, sizeof(struct msgbuf)) ;
flag = msgrcv( msqid, &buf2, recvlength ,1,0 ) ;
if ( flag <0 )
{
perror("recv message error") ;
return -1 ;
}
printf("type=%d, message=%s\n", buf2.mtype, buf2.mtext) ;
flag = msgctl( msqid, IPC_RMID,NULL) ;
if ( flag <0 )
{
perror("rm message queue error") ;
return -1 ;
}
system("ipcs -q") ;
return 0 ;
}

输出：

uid:0, gid = 0, cuid = 0, cgid= 0
read-write:666, cbytes = 1024, qnum = 2, qbytes= 16384
------ Message Queues --------
key msqid owner perms used-bytes messages
0x00000000 0 root 666 1024 2
type=3, message=good bye!
type=1, message=happy new year!
------ Message Queues --------
key msqid owner perms used-bytes messages