.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.TH TCGETSID 3 2015-08-08 "GNU" "Linux Programmer's Manual"
.SH NAME
tcgetsid \- get session ID
.SH SYNOPSIS
.BR "#define _XOPEN_SOURCE 500" "        /* See feature_test_macros(7) */"
.br
.B "#include <termios.h>"
.sp
.BI "pid_t tcgetsid(int " fd );
.SH DESCRIPTION
The function
.BR tcgetsid ()
returns the session ID of the current session that has the
terminal associated to
.I fd
as controlling terminal.
This terminal must be the controlling terminal of the calling process.
.SH RETURN VALUE
When
.I fd
refers to the controlling terminal of our session,
the function
.BR tcgetsid ()
will return the session ID of this session.
Otherwise, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EBADF
.I fd
is not a valid file descriptor.
.TP
.B ENOTTY
The calling process does not have a controlling terminal, or
it has one but it is not described by
.IR fd .
.SH VERSIONS
.BR tcgetsid ()
is provided in glibc since version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR tcgetsid ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
This function is implemented via the
.B TIOCGSID
.BR ioctl (2),
present
since Linux 2.1.71.
.SH SEE ALSO
.BR getsid (2)