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处理控制 | Process Control

posix_access

posix_access

(PHP 5 >= 5.1.0, PHP 7)

posix_access — Determine accessibility of a file

Description

bool posix_access ( string $file [, int $mode = POSIX_F_OK ] )

posix_access() checks the user's permission of a file.

Parameters

file

The name of the file to be tested.

mode

A mask consisting of one or more of POSIX_F_OK, POSIX_R_OK, POSIX_W_OK and POSIX_X_OK.

POSIX_R_OK, POSIX_W_OK and POSIX_X_OK request checking whether the file exists and has read, write and execute permissions, respectively. POSIX_F_OK just requests checking for the existence of the file.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #1 posix_access() example

This example will check if the $file is readable and writable, otherwise will print an error message.

<?php $file = 'some_file'; if (posix_access($file, POSIX_R_OK | POSIX_W_OK)) {     echo 'The file is readable and writable!'; } else {     $error = posix_get_last_error(     echo "Error $error: " . posix_strerror($error } ?>

Notes

Note: When safe mode is enabled, PHP checks whether the files or directories being operated upon have the same UID (owner) as the script that is being executed.

See Also

  • posix_get_last_error() - Retrieve the error number set by the last posix function that failed

  • posix_strerror() - Retrieve the system error message associated with the given errno

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posix_ctermid →

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Licensed under the Creative Commons Attribution License v3.0 or later.

https://secure.php.net/manual/en/function.posix-access.php