man3/tcgetsid.3

   1 '\" t
   2 .\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .TH tcgetsid 3 (date) "Linux man-pages (unreleased)"
   7 .SH NAME
   8 tcgetsid \- get session ID
   9 .SH LIBRARY
  10 Standard C library
  11 .RI ( libc ", " \-lc )
  12 .SH SYNOPSIS
  13 .nf
  14 .BR "#define _XOPEN_SOURCE 500" "        /* See feature_test_macros(7) */"
  15 .B "#include <termios.h>"
  16 .P
  17 .BI "pid_t tcgetsid(int " fd );
  18 .fi
  19 .SH DESCRIPTION
  20 The function
  21 .BR tcgetsid ()
  22 returns the session ID of the current session that has the
  23 terminal associated to
  24 .I fd
  25 as controlling terminal.
  26 This terminal must be the controlling terminal of the calling process.
  27 .SH RETURN VALUE
  28 When
  29 .I fd
  30 refers to the controlling terminal of our session,
  31 the function
  32 .BR tcgetsid ()
  33 will return the session ID of this session.
  34 Otherwise, \-1 is returned, and
  35 .I errno
  36 is set to indicate the error.
  37 .SH ERRORS
  38 .TP
  39 .B EBADF
  40 .I fd
  41 is not a valid file descriptor.
  42 .TP
  43 .B ENOTTY
  44 The calling process does not have a controlling terminal, or
  45 it has one but it is not described by
  46 .IR fd .
  47 .SH ATTRIBUTES
  48 For an explanation of the terms used in this section, see
  49 .BR attributes (7).
  50 .TS
  51 allbox;
  52 lbx lb lb
  53 l l l.
  54 Interface       Attribute       Value
  55 T{
  56 .na
  57 .nh
  58 .BR tcgetsid ()
  59 T}      Thread safety   MT-Safe
  60 .TE
  61 .SH STANDARDS
  62 POSIX.1-2008.
  63 .SH HISTORY
  64 glibc 2.1.
  65 POSIX.1-2001.
  66 .P
  67 This function is implemented via the
  68 .B TIOCGSID
  69 .BR ioctl (2),
  70 present
  71 since Linux 2.1.71.
  72 .SH SEE ALSO
  73 .BR getsid (2)