php-pcntlHow to use shared variables with the PCNTL_FORK function in PHP?

Shared variables can be used with the PCNTL_FORK function in PHP by using the shmop_open function. This function creates a shared memory segment and returns a shared memory identifier.

<?php
$shm_key = ftok(__FILE__, 't');
$shm_id = shmop_open($shm_key, "c", 0644, 1024);
?>

The code above creates a shared memory segment and returns a shared memory identifier.

1. ftok(__FILE__, 't'): This function generates a unique key based on the pathname of the current file and a character.
2. shmop_open($shm_key, "c", 0644, 1024): This function creates a shared memory segment and returns a shared memory identifier. The parameters are the key, the access mode, the permissions and the size of the segment.
3. shmop_write($shm_id, $data, 0): This function writes data to the shared memory segment. The parameters are the shared memory identifier, the data to write and the offset.
4. shmop_read($shm_id, 0, 1024): This function reads data from the shared memory segment. The parameters are the shared memory identifier, the offset and the number of bytes to read.

Helpful links

• PHP: shmop_open - Manual
• PHP: shmop_write - Manual
• PHP: shmop_read - Manual

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