1GETTID(2)                  Linux Programmer's Manual                 GETTID(2)
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NAME

6       gettid - get thread identification
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SYNOPSIS

9       #define _GNU_SOURCE
10       #include <unistd.h>
11       #include <sys/types.h>
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13       pid_t gettid(void);
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DESCRIPTION

16       gettid()  returns  the  caller's thread ID (TID).  In a single-threaded
17       process, the thread ID is equal to the process ID (PID, as returned  by
18       getpid(2)).  In a multithreaded process, all threads have the same PID,
19       but each one has a unique TID.  For further details, see the discussion
20       of CLONE_THREAD in clone(2).
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RETURN VALUE

23       On success, returns the thread ID of the calling thread.
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ERRORS

26       This call is always successful.
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VERSIONS

29       The  gettid()  system  call  first  appeared on Linux in kernel 2.4.11.
30       Library support was added in glibc 2.30.  (Earlier glibc  versions  did
31       not  provide  a  wrapper for this system call, necessitating the use of
32       syscall(2).)
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CONFORMING TO

35       gettid() is Linux-specific and should not be used in programs that  are
36       intended to be portable.
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NOTES

39       The  thread  ID  returned by this call is not the same thing as a POSIX
40       thread ID (i.e., the opaque value returned by pthread_self(3)).
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42       In a new thread group created by a clone(2) call that does not  specify
43       the  CLONE_THREAD  flag  (or,  equivalently,  a  new process created by
44       fork(2)), the new process is a thread  group  leader,  and  its  thread
45       group ID (the value returned by getpid(2)) is the same as its thread ID
46       (the value returned by gettid()).
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SEE ALSO

49       capget(2), clone(2), fcntl(2), fork(2), get_robust_list(2),  getpid(2),
50       ioprio_set(2),   perf_event_open(2),  sched_setaffinity(2),  sched_set‐
51       param(2), sched_setscheduler(2), tgkill(2), timer_create(2)
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COLOPHON

54       This page is part of release 5.07 of the Linux  man-pages  project.   A
55       description  of  the project, information about reporting bugs, and the
56       latest    version    of    this    page,    can     be     found     at
57       https://www.kernel.org/doc/man-pages/.
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61Linux                             2020-04-11                         GETTID(2)
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