# posix_access

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

posix_access — Determine accessibility of a file

### 说明

posix_access(string `$filename`, int `$flags` = 0): bool

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

### 参数

`filename`

  The name of the file to be tested.

`flags`

  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.

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 示例

示例 #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);
}
?>`

### 参见

- 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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