man3/tcgetsid.3

.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
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.TH TCGETSID 3 2010-09-10 "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 "CONFORMING TO"
POSIX.1-2001.
.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)