getpid, getppid — get process identification
#include <sys/types.h> #include <unistd.h>
pid_t
getpid( |
void); |
pid_t
getppid( |
void); |
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.
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.
clone(2), fork(2), kill(2), exec(3), mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3), credentials(7)
This page is part of release 3.33 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at http://man7.org/linux/man-pages/.
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Copyright 1993 Rickard E. Faith (faithcs.unc.edu) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. |