mirror of https://github.com/mkerrisk/man-pages
99 lines
3.0 KiB
Groff
99 lines
3.0 KiB
Groff
.\" Copyright 2003 Abhijit Menon-Sen <ams@wiw.org>
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.\" and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH GETTID 2 2021-03-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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gettid \- get thread identification
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.SH SYNOPSIS
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.nf
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.B #define _GNU_SOURCE
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.B #include <unistd.h>
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.PP
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.B pid_t gettid(void);
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.fi
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.SH DESCRIPTION
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.BR gettid ()
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returns the caller's thread ID (TID).
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In a single-threaded process, the thread ID
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is equal to the process ID (PID, as returned by
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.BR getpid (2)).
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In a multithreaded process, all threads
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have the same PID, but each one has a unique TID.
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For further details, see the discussion of
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.BR CLONE_THREAD
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in
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.BR clone (2).
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.SH RETURN VALUE
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On success, returns the thread ID of the calling thread.
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.SH ERRORS
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This call is always successful.
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.SH VERSIONS
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The
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.BR gettid ()
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system call first appeared on Linux in kernel 2.4.11.
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Library support was added in glibc 2.30.
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(Earlier glibc versions did not provide a wrapper for this system call,
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necessitating the use of
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.BR syscall (2).)
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.SH CONFORMING TO
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.BR gettid ()
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is Linux-specific and should not be used in programs that
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are intended to be portable.
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.SH NOTES
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The thread ID returned by this call is not the same thing as a
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POSIX thread ID (i.e., the opaque value returned by
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.BR pthread_self (3)).
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.PP
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In a new thread group created by a
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.BR clone (2)
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call that does not specify the
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.BR CLONE_THREAD
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flag (or, equivalently, a new process created by
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.BR fork (2)),
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the new process is a thread group leader,
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and its thread group ID (the value returned by
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.BR getpid (2))
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is the same as its thread ID (the value returned by
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.BR gettid ()).
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.SH SEE ALSO
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.BR capget (2),
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.BR clone (2),
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.BR fcntl (2),
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.BR fork (2),
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.BR get_robust_list (2),
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.BR getpid (2),
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.\" .BR kcmp (2),
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.BR ioprio_set (2),
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.\" .BR move_pages (2),
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.\" .BR migrate_pages (2),
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.BR perf_event_open (2),
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.\" .BR process_vm_readv (2),
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.\" .BR ptrace (2),
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.BR sched_setaffinity (2),
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.BR sched_setparam (2),
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.BR sched_setscheduler (2),
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.BR tgkill (2),
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.BR timer_create (2)
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