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)