无名管道：
父进程进行写，子进程读。
#include创建管道#include #include #include #include int main() { int fd[2]; int pid; char buf[128]; if(pipe(fd) == -1){ printf("Create pipe failedn"); } pid = fork(); if(pid < 0){ printf("Create child failedn"); } else if(pid > 0){ sleep(3); printf("This is fathern"); close(fd[0]); write(fd[1],"Hello My friend!n",strlen("Hello My friendn")); wait(NULL); }else{ printf("This is childn"); close(fd[1]); read(fd[0],buf,128); printf("The info are %sn",buf); exit(0); } return 0; }
利用mkfifo创建管道
函数原型：
NAME
mkfifo, mkfifoat - make a FIFO special file (a named pipe)
SYNOPSIS
#include
#include
int mkfifo(const char *pathname, mode_t mode); #include#include int mkfifoat(int dirfd, const char *pathname, mode_t mode);
DEscriptION
mkfifo() makes a FIFO special file with name pathname. mode specifies the FIFO’s permissions. It is modified by the process’s umask in the usual way: the permissions of the created file are (mode &
~umask).
A FIFO special file is similar to a pipe, except that it is created in a different way. Instead of being an anonymous communications channel, a FIFO special file is entered into the filesystem by call‐ ing mkfifo(). once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file. However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO for reading normally blocks until some other process opens the same FIFO for writing, and vice versa. See fifo(7) for non‐ blocking handling of FIFO special files.
#include消息队列#include #include #include #include int main() { if(mkfifo("./file",0600)== -1 && errno ==EEXIST){ printf("mkfifo failedn"); perror("Why"); }else{ printf("mkfifo successn"); } return 0; }
发送方：
#include#include #include #include struct msgbuf{ long mtype; char mtext[128]; }; int main() { struct msgbuf sendBuf = {111,"This is message from queuen"}; key_t key = ftok(".",'z'); printf("key = %xn",key); int msgId = msgget(key,IPC_CREAT|0777); //msgget创建消息队列 if(msgId == -1){ printf("get queue failedn"); } msgsnd(msgId,&sendBuf,strlen(sendBuf.mtext),0); //发送 struct msgbuf readBuf; msgrcv(msgId,&readBuf,sizeof(readBuf.mtext),112,0); //接收 printf("return from get:%sn",readBuf.mtext); msgctl(msgId,IPC_RMID,NULL); return 0; }
接收方：
#include共享内存#include #include #include #include struct msgbuf{ long mtype; char mtext[128]; }; int main() { struct msgbuf readBuf; key_t key = ftok(".",'z'); printf("key = %xn",key); int msgId = msgget(key,IPC_CREAT|0777); if(msgId == -1){ printf("get queue failedn"); } msgrcv(msgId,&readBuf,sizeof(readBuf.mtext),112,0); //接收 printf("read from queue:%sn",readBuf.mtext); struct msgbuf sendBuf = {111,"Thank youn"}; msgsnd(msgId,&sendBuf,strlen(sendBuf.mtext),0); //发送 msgctl(msgId,IPC_RMID,NULL); return 0; }
函数原型：
NAME
shmget - allocates a System V shared memory segment
SYNOPSIS
#include
#include
int shmget(key_t key, size_t size, int shmflg);
DEscriptION
shmget() returns the identifier of the System V shared memory segment associated with the value of the argument key. A new shared memory segment,with size equal to the value of size rounded up to a multiple of PAGE_SIZE, is created if key has the value IPC_PRIVATE or key isn’t IPC_PRIVATE, no shared memory segment corresponding to key exists, and IPC_CREAT is specified in shmflg.
If shmflg specifies both IPC_CREAT and IPC_EXCL and a shared memory segment already exists for key, then shmget() fails with errno set to EEXIST. (This is analogous to the effect of the combination O_CREAT | O_EXCL for open(2).)
NAME
shmat, shmdt - System V shared memory operations
SYNOPSIS
#include
#include
void *shmat(int shmid, const void *shmaddr, int shmflg); int shmdt(const void *shmaddr);
DEscriptION
shmat()
shmat() attaches the System V shared memory segment identified by shmid to the address space of the calling process. The attaching address is specified by shmaddr with one of the following criteria:
* If shmaddr is NULL, the system chooses a suitable (unused) page-aligned address to attach the segment. * If shmaddr isn't NULL and SHM_RND is specified in shmflg, the attach occurs at the address equal to shmaddr rounded down to the nearest multiple of SHMLBA. * Otherwise, shmaddr must be a page-aligned address at which the attach occurs.
NAME
shmat, shmdt - System V shared memory operations
SYNOPSIS
#include
#include
void *shmat(int shmid, const void *shmaddr, int shmflg); int shmdt(const void *shmaddr);
DEscriptION
shmat()
shmat() attaches the System V shared memory segment identified by shmid to
the address space of the calling process. The attaching address is speci‐
fied by shmaddr with one of the following criteria:
* If shmaddr is NULL, the system chooses a suitable (unused) page-aligned
address to attach the segment.
* If shmaddr isn't NULL and SHM_RND is specified in shmflg, the attach
occurs at the address equal to shmaddr rounded down to the nearest multi‐
ple of SHMLBA.
* Otherwise, shmaddr must be a page-aligned address at which the attach
occurs.
NAME
shmctl - System V shared memory control
SYNOPSIS
#include
#include
int shmctl(int shmid, int cmd, struct shmid_ds *buf);
DEscriptION
shmctl() performs the control operation specified by cmd on the System V shared memory segment whose identifier is given in shmid.
The buf argument is a pointer to a shmid_ds structure, defined inas follows: struct shmid_ds { struct ipc_perm shm_perm; size_t shm_segsz; time_t shm_atime; time_t shm_dtime; time_t shm_ctime; pid_t shm_cpid; pid_t shm_lpid; shmatt_t shm_nattch; ... };
写：
#include#include #include #include #include #include int main() { int shmid; char *shmaddr; key_t key; key = ftok(".",1); shmid = shmget(key,1024*4,IPC_CREAT|0666); if(shmid == -1){ printf("shmget is okn"); exit(-1); } shmaddr = shmat(shmid,0,0); printf("shmat okn"); strcpy(shmaddr,"I want to be the best people!n"); sleep(5); shmdt(shmaddr); shmctl(shmid,IPC_RMID,0); printf("quitn"); return 0; }
读：
#include#include #include #include #include #include int main() { int shmid; char *shmaddr; key_t key; key = ftok(".",1); shmid = shmget(key,1024*4,0); if(shmid == -1){ printf("shmget is okn"); exit(-1); } shmaddr = shmat(shmid,0,0); printf("shmat okn"); printf("data:%sn",shmaddr); shmdt(shmaddr); printf("quitn"); return 0; }
共享内存的查看：
ipcs -m
共享内存的删除：
ipcrm -m （shmid值）
