GETPID(2) manual page
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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.
These functions are always successful.
POSIX.1-2001,
4.3BSD, SVr4.
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)
, pid_namespaces(7)
This
page is part of release 3.78 of the Linux man-pages project. A description
of the project, information about reporting bugs, and the latest version
of this page, can be found at http://www.kernel.org/doc/man-pages/.
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