ftok

Ask for memory sharing problems!!! The code is as follows: $sysid = $shmkey = Ftok (__file__, ' t ');$flags = "C";$mode = 0766;$size = 1024;$shmid = Shmop_open ($sysid, $flags, $mode, $size);Shmop_write ($shmid, "Hello", 0);$len = Shmop_size

Name Stat, fstat, lstat-Get File statusSynopsis # Include # Include # Include Int Stat (const char *Path, Struct stat *Buf);Int fstat (int FD, Struct stat *Buf);Int lstat (const char *Path, Struct stat *Buf); Feature test macro requirements for

Multi-thread programming in Unix/Linux   1. ThreadA thread is usually called a lightweight process. Although this method is somewhat simplified, it is helpful to understand the concept of thread.Because

A message queue is a list of messages. You can add messages to a message queue.And read messages. Message Queue has certain FIFO features, but it can be implementedThe random query of messages has a greater advantage than FIFO. At the same time,

The process can read and write memory directly without any data replication. To exchange data between multiple processesInformation, the kernel sets aside a memory area, which can be mapped by the process to be accessedTo its own private address

Create a traffic signal program:   # Include # include # include # include # include # include # include # include # include # include # Define key_t doubleUnion semun {int val; struct semid_ds * Buf; ushort * array;} para;Pid_t

Shared memoryShared memory is primarily used to enable large amounts of data transfer between processes.Data structure definition for shared memory:System limits on shared memory:Shared memory vs. piping:You can see the benefits of shared memory:1.

Most of the specific implementations of shared memory are mapped to the same piece of physical memory by the memory shared between the different processes. Multiple processes map the physical memory area to their own virtual address space, which can

The ★ipc method includes pipes, message queues (message_queue), semaphores, Shared Memory (Sharememory), and sockets. IntoProcess communication mainly includes pipelines, system IPC (including message queue, signal, and shared storage), socket

Shared memory of interprocess communicationOne, what is shared memoryShared memory, as the name implies, allows two unrelated processes to access the same logical memory. Shared memory is a very efficient way to share and pass data between two

What is shared memory?shared memory allows two unrelated processes to access the same piece of physical memory . Processes can connect the same piece of shared memory to their own address space, and all processes can access addresses in shared

I. Introduction to the IPC (inter-process communication, interprocess communication) object The IPC objects for System V have shared memory, message queues, and semaphores.Note: In the IPC communication mode, each IPC object has a unique name,

"Copyright Notice: respect for the original, reproduced please retain the source: blog.csdn.net/shallnet or .../gentleliu, the article is for learning communication only, do not use for commercial purposes"System V Message Queuing is similar to

15.6 XSI IPC(1) 3 types of IPC known as XSI IPC are:1) Message Queuing2) Signal Volume3) Shared memory(2) Identifiers and keys1) Identifier: is a non-negative integer used to reference the IPC structure. is the internal name of the IPC object.2) Key:

A message queue is a linked list of messages. You can think of a message as a record, with a specific format and a specific priority. A process that has write permission to a message queue can add new messages to it by a certain rule, and a process

I. Understanding of Shared memory(1) Shared memory is one of the most efficient interprocess communication processes that can read and write directly to memory without requiring any copy of the data.(2) In order to exchange information between

https://www.ibm.com/developerworks/cn/linux/l-ipc/part3/Continue to insist, perhaps not a deep understanding, but at least to ensure that the impression.~~~~~~~~~~~~~~Message Queuing (also called Message Queuing) can overcome some of the drawbacks

1) Use the Ftok () function to obtain an ID number.2) Shmget () function to open/point to a piece of shared memory3) Shmat () maps this memory area to the virtual address space of the process.4) The SHMDT () function removes the use of this memory

One, thread synchronization condition variable what is a condition variable? Thread A waits for a condition to be established, and thread a continues to execute downward. Thread B executes the condition and wakes up thread A after the condition is

Linux Application Development-semaphore mutex programmingA corresponding function1 Create/Open Semaphore collectionFunction name Semgetfunction prototype int semget (key_t key, int nsems, int semflg)function functionGets the identifier of the