man3/tcgetsid.3

   1 .\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .TH TCGETSID 3 2021-03-22 "Linux man-pages (unreleased)"
   6 .SH NAME
   7 tcgetsid \- get session ID
   8 .SH LIBRARY
   9 Standard C library
  10 .RI ( libc ", " \-lc )
  11 .SH SYNOPSIS
  12 .nf
  13 .BR "#define _XOPEN_SOURCE 500" "        /* See feature_test_macros(7) */"
  14 .B "#include <termios.h>"
  15 .PP
  16 .BI "pid_t tcgetsid(int " fd );
  17 .fi
  18 .SH DESCRIPTION
  19 The function
  20 .BR tcgetsid ()
  21 returns the session ID of the current session that has the
  22 terminal associated to
  23 .I fd
  24 as controlling terminal.
  25 This terminal must be the controlling terminal of the calling process.
  26 .SH RETURN VALUE
  27 When
  28 .I fd
  29 refers to the controlling terminal of our session,
  30 the function
  31 .BR tcgetsid ()
  32 will return the session ID of this session.
  33 Otherwise, \-1 is returned, and
  34 .I errno
  35 is set to indicate the error.
  36 .SH ERRORS
  37 .TP
  38 .B EBADF
  39 .I fd
  40 is not a valid file descriptor.
  41 .TP
  42 .B ENOTTY
  43 The calling process does not have a controlling terminal, or
  44 it has one but it is not described by
  45 .IR fd .
  46 .SH VERSIONS
  47 .BR tcgetsid ()
  48 is provided in glibc since version 2.1.
  49 .SH ATTRIBUTES
  50 For an explanation of the terms used in this section, see
  51 .BR attributes (7).
  52 .ad l
  53 .nh
  54 .TS
  55 allbox;
  56 lbx lb lb
  57 l l l.
  58 Interface       Attribute       Value
  59 T{
  60 .BR tcgetsid ()
  61 T}      Thread safety   MT-Safe
  62 .TE
  63 .hy
  64 .ad
  65 .sp 1
  66 .SH STANDARDS
  67 POSIX.1-2001, POSIX.1-2008.
  68 .SH NOTES
  69 This function is implemented via the
  70 .B TIOCGSID
  71 .BR ioctl (2),
  72 present
  73 since Linux 2.1.71.
  74 .SH SEE ALSO
  75 .BR getsid (2)