posix_access
(PHP 5 >= 5.1.0)
posix_access — Determine accessibility of a file
Description
$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_OKandPOSIX_X_OK.POSIX_R_OK,POSIX_W_OKandPOSIX_X_OKrequest checking whether the file exists and has read, write and execute permissions, respectively.POSIX_F_OKjust 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
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для управления процессами программ
- POSIX
- posix_access
- posix_ctermid
- posix_errno
- posix_get_last_error
- posix_getcwd
- posix_getegid
- posix_geteuid
- posix_getgid
- posix_getgrgid
- posix_getgrnam
- posix_getgroups
- posix_getlogin
- posix_getpgid
- posix_getpgrp
- posix_getpid
- posix_getppid
- posix_getpwnam
- posix_getpwuid
- posix_getrlimit
- posix_getsid
- posix_getuid
- posix_initgroups
- posix_isatty
- posix_kill
- posix_mkfifo
- posix_mknod
- posix_setegid
- posix_seteuid
- posix_setgid
- posix_setpgid
- posix_setrlimit
- posix_setsid
- posix_setuid
- posix_strerror
- posix_times
- posix_ttyname
- posix_uname
Коментарии
It should be noted that this function performs access checks based on the real UID and real GID of the process running PHP. These aren't necessarily the same as the effective UID and GID.
In other words, it may well be that access() returns “true” for a particular permission, but an fopen() operation which requires the same permission will fail, and vice versa.
Keep that in mind if you use access() for such checks.