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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  sys-
       tem calls when a process calls getpid() repeatedly.  Normally this caching is invisible, but its correct opera-
       tion 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  discus-
       sion  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 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2008-09-23                         GETPID(2)