gen/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 isatty ,
  40 .Nm ttyname ,
  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 int
  48 .Fo isatty
  49 .Fa "int fildes"
  50 .Fc
  51 .Ft char *
  52 .Fo ttyname
  53 .Fa "int fildes"
  54 .Fc
  55 .Ft int
  56 .Fo ttyslot
  57 .Fa void
  58 .Fc
  59 .Sh DESCRIPTION
  60 These functions operate on the system file descriptors for terminal
  61 type devices.
  62 These descriptors are not related to the standard
  63 .Tn I/O
  64 .Dv FILE
  65 typedef, but refer to the special device files found in
  66 .Pa /dev
  67 and named
  68 .Pa /dev/tty Ns Ar xx
  69 and for which an entry exists
  70 in the initialization file
  71 .Pa /etc/ttys .
  72 (See
  73 .Xr ttys 5 . )
  74 .Pp
  75 The
  76 .Fn isatty
  77 function
  78 determines if the file descriptor
  79 .Fa fildes
  80 refers to a valid
  81 terminal type device.
  82 .Pp
  83 The
  84 .Fn ttyname
  85 function
  86 gets the related device name of
  87 a file descriptor for which
  88 .Fn isatty
  89 is true.
  90 .Pp
  91 The
  92 .Fn ttyslot
  93 function
  94 fetches the current process' control terminal number from the
  95 .Xr ttys 5
  96 file entry.
  97 .Sh RETURN VALUES
  98 The
  99 .Fn ttyname
 100 function
 101 returns the null terminated name if the device is found and
 102 .Fn isatty
 103 is true; otherwise, a
 104 .Dv NULL
 105 pointer is returned.
 106 .Pp
 107 The
 108 .Fn ttyslot
 109 function returns the unit number of the device file if found;
 110 otherwise, the value zero is returned.
 111 .Sh FILES
 112 .Bl -tag -width /etc/ttys -compact
 113 .It Pa /dev/\(**
 114 .It Pa /etc/ttys
 115 .El
 116 .Sh SEE ALSO
 117 .Xr ioctl 2 ,
 118 .Xr ttys 5
 119 .Sh HISTORY
 120 A
 121 .Fn isatty ,
 122 .Fn ttyname ,
 123 and
 124 .Fn ttyslot
 125 function
 126 appeared in
 127 .At v7 .
 128 .Sh BUGS
 129 The
 130 .Fn ttyname
 131 function leaves its result in an internal static object and returns
 132 a pointer to that object.
 133 Subsequent calls to
 134 .Fn ttyname
 135 will modify the same object.