# posix_access

(PHP 5 >= 5.1.0, PHP 7)

posix_access — Determine accessibility of a file

### 说明

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

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

### 参数

`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.

### 返回值

成功时返回 `TRUE`， 或者在失败时返回 `FALSE`。

### 范例

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);
    }

    ?>

### 注释

> Note: 当启用 安全模式时， PHP 会检查被操作的文件或目录是否与被执行的脚本有相同的 UID（所有者）。

### 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