man3/tcgetsid.3

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  23 .TH TCGETSID 3 2008-06-14 "GNU" "Linux Programmer's Manual"
  24 .SH NAME
  25 tcgetsid \- get session ID
  26 .SH SYNOPSIS
  27 .B #define _XOPEN_SOURCE 500
  28 .br
  29 .B "#include <termios.h>"
  30 .sp
  31 .BI "pid_t tcgetsid(int " fd );
  32 .SH DESCRIPTION
  33 The function
  34 .BR tcgetsid ()
  35 returns the session ID of the current session that has the
  36 terminal associated to
  37 .I fd
  38 as controlling terminal.
  39 This terminal must be the controlling terminal of the calling process.
  40 .SH "RETURN VALUE"
  41 When
  42 .I fd
  43 refers to the controlling terminal of our session,
  44 the function
  45 .BR tcgetsid ()
  46 will return the session ID of this session.
  47 Otherwise, \-1 is returned, and
  48 .I errno
  49 is set appropriately.
  50 .SH ERRORS
  51 .TP
  52 .B EBADF
  53 .I fd
  54 is not a valid file descriptor.
  55 .TP
  56 .B ENOTTY
  57 The calling process does not have a controlling terminal, or
  58 it has one but it is not described by
  59 .IR fd .
  60 .SH VERSIONS
  61 .BR tcgetsid ()
  62 is provided in glibc since version 2.1.
  63 .SH "CONFORMING TO"
  64 POSIX.1-2001.
  65 .SH NOTES
  66 This function is implemented via the
  67 .B TIOCGSID
  68 .BR ioctl (2),
  69 present
  70 since Linux 2.1.71.
  71 .SH "SEE ALSO"
  72 .BR getsid (2)