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 sup-
       port 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 3.25 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)