PHP Manual: posix

function posix_fpathconf(resource|int $file_descriptor, int $name): int|false

Returns the value of a configurable limit from name for file_descriptor.

file_descriptor: The file descriptor, which is expected to be either a file resource or an int. An int will be assumed to be a file descriptor that can be passed directly to the underlying system call.
name: The name of the configurable limit, one of the following. POSIX_PC_LINK_MAX, POSIX_PC_MAX_CANON, POSIX_PC_MAX_INPUT, POSIX_PC_NAME_MAX, POSIX_PC_PATH_MAX, POSIX_PC_PIPE_BUF, POSIX_PC_CHOWN_RESTRICTED, POSIX_PC_NO_TRUNC, POSIX_PC_ALLOC_SIZE_MIN, POSIX_PC_SYMLINK_MAX.

Returns the configurable limit or false.

Throws a ValueError when resource is invalid.

Version	Description
8.5.0	Now sets `last_error` to `EBADF` and raises an `E_WARNING` when an invalid file descriptor is encountered.

Example #1 posix_fpathconf() example

This example will get the max path name's length in bytes for the current dir.

<?php
$fd = fopen(__DIR__, "r");
echo posix_fpathconf($fd, POSIX_PC_PATH_MAX);
?>

The above example will output:

posix_fpathconf