(PHP 5 >= 5.1.0, PHP 7) Determine accessibility of a file

(PHP 4, PHP 5, PHP 7) Pathname of current directory

(PHP 4, PHP 5, PHP 7) Set process group id for job control

(PHP 4, PHP 5, PHP 7) Get process group id for job control

(PHP 4, PHP 5, PHP 7) Return the real user ID of the current process

(PHP 4 >= 4.0.2, PHP 5, PHP 7) Set the effective GID of the current process

(PHP 4, PHP 5, PHP 7) Create a fifo special file (a named pipe)

(PHP 4 >= 4.2.0, PHP 5, PHP 7) Retrieve the error number set by the last posix function that failed

(PHP 4 >= 4.0.2, PHP 5, PHP 7) Set the effective UID of the current process

(PHP 4, PHP 5, PHP 7) Get path name of controlling terminal