gen/FreeBSD/ttyname.3

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  32 .\"     @(#)ttyname.3   8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/gen/ttyname.3,v 1.10 2002/12/18 13:33:02 ru Exp $
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  35 .Dd June 4, 1993
  36 .Dt TTYNAME 3
  37 .Os
  38 .Sh NAME
  39 .Nm ttyname ,
  40 .Nm isatty ,
  41 .Nm ttyslot
  42 .Nd get name of associated terminal (tty) from file descriptor
  43 .Sh LIBRARY
  44 .Lb libc
  45 .Sh SYNOPSIS
  46 .In unistd.h
  47 .Ft char *
  48 .Fn ttyname "int fd"
  49 .Ft int
  50 .Fn isatty "int fd"
  51 .Ft int
  52 .Fn ttyslot void
  53 .Sh DESCRIPTION
  54 These functions operate on the system file descriptors for terminal
  55 type devices.
  56 These descriptors are not related to the standard
  57 .Tn I/O
  58 .Dv FILE
  59 typedef, but refer to the special device files found in
  60 .Pa /dev
  61 and named
  62 .Pa /dev/tty Ns Ar xx
  63 and for which an entry exists
  64 in the initialization file
  65 .Pa /etc/ttys .
  66 (See
  67 .Xr ttys 5 . )
  68 .Pp
  69 The
  70 .Fn isatty
  71 function
  72 determines if the file descriptor
  73 .Fa fd
  74 refers to a valid
  75 terminal type device.
  76 .Pp
  77 The
  78 .Fn ttyname
  79 function
  80 gets the related device name of
  81 a file descriptor for which
  82 .Fn isatty
  83 is true
  84 .Pp
  85 The
  86 .Fn ttyslot
  87 function
  88 fetches the current process' control terminal number from the
  89 .Xr ttys 5
  90 file entry.
  91 .Sh RETURN VALUES
  92 The
  93 .Fn ttyname
  94 function
  95 returns the null terminated name if the device is found and
  96 .Fn isatty
  97 is true; otherwise
  98 a
  99 .Dv NULL
 100 pointer is returned.
 101 .Pp
 102 The
 103 .Fn ttyslot
 104 function
 105 returns the unit number of the device file if found; otherwise
 106 the value zero is returned.
 107 .Sh FILES
 108 .Bl -tag -width /etc/ttys -compact
 109 .It Pa /dev/\(**
 110 .It Pa /etc/ttys
 111 .El
 112 .Sh SEE ALSO
 113 .Xr ioctl 2 ,
 114 .Xr ttys 5
 115 .Sh HISTORY
 116 A
 117 .Fn isatty ,
 118 .Fn ttyname ,
 119 and
 120 .Fn ttyslot
 121 function
 122 appeared in
 123 .At v7 .
 124 .Sh BUGS
 125 The
 126 .Fn ttyname
 127 function leaves its result in an internal static object and returns
 128 a pointer to that object.
 129 Subsequent calls to
 130 .Fn ttyname
 131 will modify the same object.