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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

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