man3/tcgetsid.3

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  23 .TH TCGETSID 3 2003-01-30 "GNU" "Linux Programmer's Manual"
  24 .SH NAME
  25 tcgetsid \- get session ID
  26 .SH SYNOPSIS
  27 .sp
  28 .BR "#include <termios.h>"
  29 .sp
  30 .BI "pid_t tcgetsid(int " fd );
  31 .SH DESCRIPTION
  32 The function
  33 .BR tcgetsid ()
  34 returns the session ID of the current session that has the
  35 terminal associated to
  36 .I fd
  37 as controlling terminal.
  38 This terminal must be the controlling terminal of the calling process.
  39 .SH "RETURN VALUE"
  40 When
  41 .I fd
  42 refers to the controlling terminal of our session,
  43 the function
  44 .BR tcgetsid ()
  45 will return the session ID of this session.
  46 Otherwise, \-1 is returned, and
  47 .I errno
  48 is set appropriately.
  49 .SH ERRORS
  50 .TP
  51 .B EBADF
  52 .I fd
  53 is not a valid file descriptor.
  54 .TP
  55 .B ENOTTY
  56 The calling process does not have a controlling terminal, or
  57 it has one but it is not described by
  58 .IR fd .
  59 .SH NOTES
  60 This function is implemented via the TIOCGSID
  61 .BR ioctl (2),
  62 present
  63 since Linux 2.1.71.
  64 .SH "CONFORMING TO"
  65 POSIX.1-2001
  66 .SH "SEE ALSO"
  67 .BR getsid (2)