Section: Linux Programmer's Manual (2)
gettid - get thread identification
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
In a multithreaded process, all threads
have the same PID, but each one has a unique TID.
For further details, see the discussion of
On success, returns the thread ID of the calling thread.
This call is always successful.
system call first appeared on Linux in kernel 2.4.11.
Library support was added in glibc 2.30.
(Earlier glibc versions did not provide a wrapper for this system call,
necessitating the use of
is Linux-specific and should not be used in programs that
are intended to be portable.
The thread ID returned by this call is not the same thing as a
POSIX thread ID (i.e., the opaque value returned by
In a new thread group created by a
call that does not specify the
flag (or, equivalently, a new process created by
the new process is a thread group leader,
and its thread group ID (the value returned by
is the same as its thread ID (the value returned by
This page is part of release 5.02 of the Linux
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at