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gettid(2) System Calls Manual gettid(2) gettid - get thread identification
Standard C library (libc, -lc)
#define _GNU_SOURCE #include <unistd.h> pid_t gettid(void);
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).
On success, returns the thread ID of the calling thread.
This call is always successful.
Linux.
Linux 2.4.11, glibc 2.30.
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()).
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_setparam(2), sched_setscheduler(2), tgkill(2), timer_create(2)
This page is part of the man-pages (Linux kernel and C library user-space interface documentation) project. Information about the project can be found at ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report for this manual page, see ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩. This page was obtained from the tarball man-pages-6.15.tar.gz fetched from ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on 2025-08-11. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org Linux man-pages 6.15 2025-05-17 gettid(2) Pages that refer to this page: kill(1), strace(1), capget(2), clone(2), F_GETSIG(2const), futex(2), getpid(2), get_robust_list(2), ioprio_set(2), PR_SET_NAME(2const), ptrace(2), sched_setaffinity(2), sched_setparam(2), sched_setscheduler(2), seccomp(2), set_tid_address(2), syscalls(2), timer_create(2), tkill(2), id_t(3type), pthread_self(3), sd_event_new(3), proc_pid_status(5), proc_pid_task(5), cgroups(7), cpuset(7), pthreads(7)
| HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. | |