DevConf 2015


(PHP 5 >= 5.1.0)

posix_access Determine accessibility of a file


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

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



The name of the file to be tested.


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.

Valor Retornado

Retorna TRUE em caso de sucesso ou FALSE em caso de falha.


Exemplo #1 posix_access() example

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



if (
posix_access($filePOSIX_R_OK POSIX_W_OK)) {
'The file is readable and writable!';

} else {
$error posix_get_last_error();

"Error $error: " posix_strerror($error);



Nota: Quando o safe-mode está ativo, o PHP verifica se os arquivo(s) ou diretórios que estão usados na operação tem o mesmo UID (proprietário) do script que está sendo executado.

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User Contributed Notes 1 note

unixguy at earth dot com
11 months ago
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.
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