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PHP : Function Reference : POSIX Functions

POSIX Functions


This module contains an interface to those functions defined in the IEEE 1003.1 (POSIX.1) standards document which are not accessible through other means. POSIX.1 for example defined the open(), read(), write() and close() functions, too, which traditionally have been part of PHP 3 for a long time. Some more system specific functions have not been available before, though, and this module tries to remedy this by providing easy access to these functions.


Sensitive data can be retrieved with the POSIX functions, e.g. posix_getpwnam() and friends. None of the POSIX function perform any kind of access checking when safe mode is enabled. It's therefore strongly advised to disable the POSIX extension at all (use --disable-posix in your configure line) if you're operating in such an environment.


This extension is not available on Windows platforms.


POSIX functions are enabled by default. You can disable POSIX-like functions with --disable-posix.

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

POSIX_F_OK (integer)
Check whether the file exists.
POSIX_R_OK (integer)
Check whether the file exists and has read permissions.
POSIX_W_OK (integer)
Check whether the file exists and has write permissions.
POSIX_X_OK (integer)
Check whether the file exists and has execute permissions.
POSIX_S_IFBLK (integer)
Block special file
POSIX_S_IFCHR (integer)
Character special file
POSIX_S_IFIFO (integer)
FIFO (named pipe) special file
POSIX_S_IFREG (integer)
Normal file
POSIX_S_IFSOCK (integer)

These constants are available since PHP 5.1.0. Please also note that some of them may not be available in your system.

See Also

The section about Process Control Functions maybe of interest for you.

Table of Contents

posix_access — Determine accessibility of a file
posix_ctermid — Get path name of controlling terminal
posix_get_last_error — Retrieve the error number set by the last posix function that failed
posix_getcwd — Pathname of current directory
posix_getegid — Return the effective group ID of the current process
posix_geteuid — Return the effective user ID of the current process
posix_getgid — Return the real group ID of the current process
posix_getgrgid — Return info about a group by group id
posix_getgrnam — Return info about a group by name
posix_getgroups — Return the group set of the current process
posix_getlogin — Return login name
posix_getpgid — Get process group id for job control
posix_getpgrp — Return the current process group identifier
posix_getpid — Return the current process identifier
posix_getppid — Return the parent process identifier
posix_getpwnam — Return info about a user by username
posix_getpwuid — Return info about a user by user id
posix_getrlimit — Return info about system resource limits
posix_getsid — Get the current sid of the process
posix_getuid — Return the real user ID of the current process
posix_initgroups — Calculate the group access list
posix_isatty — Determine if a file descriptor is an interactive terminal
posix_kill — Send a signal to a process
posix_mkfifo — Create a fifo special file (a named pipe)
posix_mknod — Create a special or ordinary file (POSIX.1)
posix_setegid — Set the effective GID of the current process
posix_seteuid — Set the effective UID of the current process
posix_setgid — Set the GID of the current process
posix_setpgid — Set process group id for job control
posix_setsid — Make the current process a session leader
posix_setuid — Set the UID of the current process
posix_strerror — Retrieve the system error message associated with the given errno
posix_times — Get process times
posix_ttyname — Determine terminal device name
posix_uname — Get system name

Code Examples / Notes » ref.posix


That is not part of POSIX, those are only present as you listed on linux systems - some other systems have a /proc with different things in it (sometimes stuff that's symbolic links on linux will be hardlinks, textfiles on linux will be binary, or different files with different information) or none at all


don't forget that in posix systems you can use /proc/$process_id/
with it you can make somethings like:
if ($pid==0){
if (strpos(file_get_contents("/proc/$PPID/cmdline"),'php')===false) echo "parent pid die";
// forked
with this you can use some libs that block signal or some bad signal handling or zombies process or anything you can think :)

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