gen/FreeBSD/ttyname.3

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  28 .\"     @(#)ttyname.3   8.1 (Berkeley) 6/4/93
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  31 .Dd July 18, 2014
  32 .Dt TTYNAME 3
  33 .Os
  34 .Sh NAME
  35 .Nm ttyname ,
  36 .Nm ttyname_r ,
  37 .Nm isatty
  38 .Nd get name of associated terminal (tty) from file descriptor
  39 .Sh LIBRARY
  40 .Lb libc
  41 .Sh SYNOPSIS
  42 .In unistd.h
  43 .Ft char *
  44 .Fn ttyname "int fd"
  45 .Ft int
  46 .Fn ttyname_r "int fd" "char *buf" "size_t len"
  47 .Ft int
  48 .Fn isatty "int fd"
  49 .Sh DESCRIPTION
  50 These functions operate on file descriptors for terminal type devices.
  51 .Pp
  52 The
  53 .Fn isatty
  54 function
  55 determines if the file descriptor
  56 .Fa fd
  57 refers to a valid
  58 terminal type device.
  59 .Pp
  60 The
  61 .Fn ttyname
  62 function
  63 gets the related device name of
  64 a file descriptor for which
  65 .Fn isatty
  66 is true.
  67 .Pp
  68 The
  69 .Fn ttyname
  70 function
  71 returns the name stored in a static buffer which will be overwritten
  72 on subsequent calls.
  73 The
  74 .Fn ttyname_r
  75 function
  76 takes a buffer and length as arguments to avoid this problem.
  77 .Sh RETURN VALUES
  78 The
  79 .Fn isatty
  80 function returns 1 if
  81 .Fa fd
  82 refers to a terminal type device;
  83 otherwise, it returns 0 and may set
  84 .Va errno
  85 to indicate the error.
  86 The
  87 .Fn ttyname
  88 function
  89 returns the null terminated name if the device is found and
  90 .Fn isatty
  91 is true; otherwise
  92 a
  93 .Dv NULL
  94 pointer is returned.
  95 The
  96 .Fn ttyname_r
  97 function returns 0 if successful.
  98 Otherwise an error number is returned.
  99 .Sh ERRORS
 100 These functions may fail if:
 101 .Bl -tag -width Er
 102 .It Bq Er EBADF
 103 The
 104 .Fa fd
 105 argument
 106 is not a valid file descriptor.
 107 .It Bq Er ENOTTY
 108 The file associated with
 109 .Fa fd
 110 is not a terminal.
 111 .El
 112 .Pp
 113 Additionally,
 114 .Fn ttyname_r
 115 may fail if:
 116 .Bl -tag -width Er
 117 .It Bq Er ERANGE
 118 The
 119 .Fa bufsize
 120 argument
 121 is smaller than the length of the string to be returned.
 122 .El
 123 .Sh SEE ALSO
 124 .Xr ioctl 2 ,
 125 .Xr ptsname 3 ,
 126 .Xr tcgetattr 3 ,
 127 .Xr tty 4 ,
 128 .Xr ttys 5
 129 .Sh HISTORY
 130 The
 131 .Fn isatty
 132 and
 133 .Fn ttyname
 134 functions
 135 appeared in
 136 .At v7 .
 137 The
 138 .Fn ttyname_r
 139 function
 140 appeared in
 141 .Fx 6.0 .