   #PHP Manual Function Reference session_write_close shmop_close

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XCVI. Shared Memory Functions

Introduction

   Shmop is an easy to use set of functions that allows PHP to read,
   write, create and delete Unix shared memory segments. Note that
   versions of Windows previous to Windows 2000 do not support shared
   memory.

     Note: In PHP 4.0.3, these functions were prefixed by shm rather
     than shmop.

Requirements

   No external libraries are needed to build this extension.

Installation

   To use shmop you will need to compile PHP with the --enable-shmop
   parameter in your configure line.

Runtime Configuration

   This extension has no configuration directives defined in php.ini.

Resource Types

Predefined Constants

   This extension has no constants defined.

Examples

   Example 1. Shared Memory Operations Overview
   <?php

   // Create 100 byte shared memory block with system id if 0xff3
   $shm_id = shmop_open(0xff3, "c", 0644, 100);
   if (!$shm_id) {
       echo "Couldn't create shared memory segment\n";
   }
   // Get shared memory block's size
   $shm_size = shmop_size($shm_id);
   echo "SHM Block Size: " . $shm_size . " has been created.\n";
   // Lets write a test string into shared memory
   $shm_bytes_written = shmop_write($shm_id, "my shared memory block",
   0);
   if ($shm_bytes_written != strlen("my shared memory block")) {
       echo "Couldn't write the entire length of data\n";
   }
   // Now lets read the string back
   $my_string = shmop_read($shm_id, 0, $shm_size);
   if (!$my_string) {
       echo "Couldn't read from shared memory block\n";
   }
   echo "The data inside shared memory was: " . $my_string . "\n";
   //Now lets delete the block and close the shared memory segment
   if (!shmop_delete($shm_id)) {
       echo "Couldn't mark shared memory block for deletion.";
   }
   shmop_close($shm_id);

   ?>

   Table of Contents
   shmop_close -- Close shared memory block
   shmop_delete -- Delete shared memory block
   shmop_open -- Create or open shared memory block
   shmop_read -- Read data from shared memory block
   shmop_size -- Get size of shared memory block
   shmop_write -- Write data into shared memory block
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