GETPID(2)						     Linux Programmer's Manual							 GETPID(2)

NAME

       getpid, getppid - get process identification

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       pid_t getpid(void);
       pid_t getppid(void);

DESCRIPTION

       getpid() returns the process ID of the calling process.	(This is often used by routines that generate unique temporary filenames.)

       getppid() returns the process ID of the parent of the calling process.

ERRORS

       These functions are always successful.

CONFORMING TO

       POSIX.1-2001, 4.3BSD, SVr4.

NOTES

       Since glibc version 2.3.4, the glibc wrapper function for getpid() caches PIDs, so as to avoid additional system calls when a process calls
       getpid() repeatedly.  Normally this caching is invisible, but its correct operation relies on support in the wrapper functions for fork(2),
       vfork(2),  and  clone(2): if an application bypasses the glibc wrappers for these system calls by using syscall(2), then a call to getpid()
       in the child will return the wrong value (to be precise: it will return the PID of the parent process).	See also clone(2)  for	discussion
       of a case where getpid() may return the wrong value even when invoking clone(2) via the glibc wrapper function.

SEE ALSO

       clone(2), fork(2), kill(2), exec(3), mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3), credentials(7)

COLOPHON

       This  page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2008-09-23								 GETPID(2)