gettid(2) System Calls Manual gettid(2)
NAME
gettid - get thread identification
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#define _GNU_SOURCE
#include <unistd.h>
pid_t gettid(void);
DESCRIPTION
gettid() returns the caller's thread ID (TID). In a single-threaded
process, the thread ID is equal to the process ID (PID, as returned by
getpid(2)). In a multithreaded process, all threads have the same PID,
but each one has a unique TID. For further details, see the discussion
of CLONE_THREAD in clone(2).
RETURN VALUE
On success, returns the thread ID of the calling thread.
ERRORS
This call is always successful.
STANDARDS
Linux.
HISTORY
Linux 2.4.11, glibc 2.30.
NOTES
The thread ID returned by this call is not the same thing as a POSIX
thread ID (i.e., the opaque value returned by pthread_self(3)).
In a new thread group created by a clone(2) call that does not specify
the CLONE_THREAD flag (or, equivalently, a new process created by
fork(2)), the new process is a thread group leader, and its thread group
ID (the value returned by getpid(2)) is the same as its thread ID (the
value returned by gettid()).
SEE ALSO
capget(2), clone(2), fcntl(2), fork(2), get_robust_list(2), getpid(2),
ioprio_set(2), perf_event_open(2), sched_setaffinity(2), sched_set-
param(2), sched_setscheduler(2), tgkill(2), timer_create(2)
Linux man-pages 6.9.1 2024-05-02 gettid(2)
Generated by dwww version 1.16 on Tue Dec 16 04:18:32 CET 2025.