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

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

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

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

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

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

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

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

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

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