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



NAME
       getpid, getppid - get process identification

SYNOPSIS
       #include 
       #include 

       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 dis-
       cussion	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),  tmp-
       file(3), tmpnam(3), credentials(7)

COLOPHON
       This  page  is  part of release 3.22 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)