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.TH PTHREAD_SELF 3 2008-10-24 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_self \- obtain ID of the calling thread
.SH SYNOPSIS
.nf
.B #include <pthread.h>

.B pthread_t pthread_self(void);
.sp
Compile and link with \fI\-pthread\fP.
.SH DESCRIPTION
The
.BR pthread_self ()
function returns the ID of the calling thread.
This is the same value that is returned in
.IR *thread
in the
.BR pthread_create (3)
call that created this thread.
.SH RETURN VALUE
This function always succeeds, returning the calling thread's ID.
.SH ERRORS
This function always succeeds.
.SH CONFORMING TO
POSIX.1-2001.
.SH NOTES
POSIX.1 allows an implementation wide freedom in choosing
the type used to represent a thread ID;
for example, representation using either an arithmetic type or
a structure is permitted.
Therefore, variables of type
.I pthread_t
can't portably be compared using the C equality operator (\fB==\fP);
use
.BR pthread_equal (3)
instead.

Thread identifiers should be considered opaque:
any attempt to use a thread ID other than in pthreads calls
is non-portable and can lead to unspecified results.

Thread IDs are only guaranteed to be unique within a process.
A thread ID may be reused after a terminated thread has been joined,
or a detached thread has terminated.

The thread ID returned by
.BR pthread_self ()
is not the same thing as the kernel thread ID returned by a call to
.BR gettid (2).
.SH SEE ALSO
.BR pthread_create (3),
.BR pthread_equal (3),
.BR pthreads (7)
.SH COLOPHON
This page is part of release 3.22 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
